Glyph renaming - disable auto-bleed in all contexts

This is my suggestion, as an expansion of @JoesCat's #524.  I have fixed the minor issue with the function prototype, but more importantly, disabled auto-rename in all contexts; not only Python scripting but also native scripting *and the GUI*.  This brings it into line with my own preferences and issue #523.  The code to do the auto-renaming still exists, but with this patch it will not execute; I'd support a future feature request to make it available as a separate command distinct from regular rename.

I've tested this to the extent possible and am reasonably sure it won't create inconsistent substitution tables; that bit of existing code turns out to be better-designed than I had feared.