CHANGES FROM VERSION 5.0

IMPROVEMENTS
- A significant performance improvement for both 2D and 3D modes, giving a generally smoother display (though with a bit more lag when rotating to a new projection). GUI menus in particular should now be extremely fluid. This is achieved with a combination of code adjustments and recommending that users do NOT use the "--enable-new-depsgraph" switch in their Windows shortcut or Linux alias.
	The small downside of disabling the switch is that this means there will sometimes be harmless "DAG zero" messages in the terminal when loading data (usually when loading data for a second time). These have been reduced, but removing them entirely appears to be impossible. Therfore loading data also prints a notification that these messages can be ignored.

- Changed the behaviour of miriad regarding the graphical output. Previously it would override the user's choice of XSERVE or postscript depending on whether the Quick or Full modes were used. This made the user's choice almost pointless (the only thing this did was set the input text files). Now it actually uses the user's choice, only overriding the case of using XSERVE for multiple regions. In that case it disables the graphical output, to prevent the case of overwhelming the user with potentially hundreds of windows. 
	There is also now a "None" option available directly in the menu, if no graphical output is required.

- Prevented the user from being able to delete protected objects (regions, planes, maps, etc.) with the X key on the keyboard. This prevents them from deleting, e.g., the wireframe region outlines but not the solid region objects, which could lead to leftover mask regions which the user couldn't even select, resulting in a bizarre appearance of the file. The spacebar menu is still available but this gives at least some additional protection; of course, really only the FRELLED GUI should be used for deleting objects as this ensures things are deleted cleanly and correctly.

- When selecting FITS files from the GUI (the main, secondary, and/or analysis file) they are now automatically checked for two common problems : lengthy headers and 4 axes. If either problem is found, the user is warned to use a new scipt "FixCommonProblems.py" to correct these issues. The 4 axes problem is already known, but very long "HISTORY" entries in the FITS header can cause particular problems for astropy/spectral-cube, making some operations inordinately slow without causing a fatal error (especially importing and exporting regions). The script produces a new FITS file leaving the original file intact, though the user will have to execute this manually.

- The distance clipping in the viewport has been increased from 1000 to 10000, preventing large cubes from being only partially visible.


BUGFIXES
- Corrected bugs on Linux that prevented all miriad operations from working. Apparently the syntax for system commands is slightly different on WSL to actual Linux (how this apparently didn't matter in earlier testing I have no idea).

- There should now no longer be excessive warning messages incorrectly complaining that the miriad file doesn't exist and suchlike. If you give the miriad file selector a FITS file to convert, it should initially report that the file needs to be converted, but that's about it.

- No more warnings about the minimum value not being allowed to exceed the maximum when generating renzograms, since these only use the minimum contour value anyway.

- Importing regions no longer pointlessly prints out the current world coordinates.

- Exporting regions no longer overwrites any existing mask files. If no regions are selected, no files are written at all. When files are produced, they are given the _00N extension. Importing files always uses the file with the highest number.

- Loading data should no longer cause problems when adding new objects via the spacebar menu. Previously creating new built-in Blender primitives (planes, cubes, etc.) was somehow corrupted so that all vertices were created at the same point. This doesn't affect FRELLED operations in any way but it's nice to have it fixed.
 


DOCUMENTATION AND CODING CHANGES
- Corrected entries in the manual and help files which claimed that only the FITS file used for visualisation/analysis (when entered into the miriad file selector box) would be automatically converted to a miriad file. This was true at some early development stage, but hasn't been the case for a long time. Entering the name of any FITS file here will cause miriad to automatically convert it to miriad's own file format, when pressing the miriad Quick or Full buttons, so long as the miriad file doesn't already exist.

- All drop-down menus now include their name in the drop-down field, for extra clarity on what they are.

- Updated help files to make it more explicit that when creating blanks for a new file, this has to be done for 3D and 2D modes separately.

- Changed the 3DViewAuto.py script to ThreeDViewAuto.py, which is now imported as a function in the ModalViews script and elsewhere (a function can't have a name beginning with a numeric character). 

- The append script (called by the button in the "Developer" tab, "Volumetric setup" panel) now sets the imported X-ray material, used by isosurfaces, to have a fake user. This prevents it from being accidentally deleted, useful when restoring a corrupted file or setting up a new one. Similarly, it now links the master camera rig correctly to the 3D scene (where it's supposed to be), again preventing it from being deleted accidentally as Blender wipes unlinked objects on saving.

- The help files and wiki for the "Camera animation control" panel ("Figures" tab) now note that the distance clipping can sometimes be incorrect, resulting in part or all of the data being hidden. They document that this can be fixed by manually adjusting the distance parameter.

- The wiki now notes that all GUI operations can also be accessed via Blender's all-purpose spacebar menu. Type in the name of an operator to find it, and you can then execute it from the pop-up menu without having to use the main GUI tool shelf at all. This can be useful if you want to avoid navigating the GUI, or if you want to keep it hidden but still want (for example) to add regions.