* improved rendering performance using shaders, including
dynamically updated shaders based on settings
(see data/shaders directory)
* implemented shaders for menus, labels, selection indicators,
background, and other graphics that were not using shaders.
* consolidated textures used for labels and selection indicators
to one texture, which helps performance
* added memory checking to help avoid crashing when memory is
low or not available
* cleaned up code base, took out extraneous preprocessor code and
code that was not used.
* refactor pmg_tk.Settings
* Do not clear atom names with chempy.champ.assign.amber99
* fix some plugin manager exception handling
* fix create with name=None
* Plugin override search path: Always include "startup"
from installation directory in plugin search path
* Movie > Program > Scene Loop > Nutate > by degrees
* ObjectMeshRenderImpl refactoring: color isomesh and isodot with
mesh_color and dot_color settings
* merging alignment objects: eliminate orphaned atoms
* fix cealign alignment object creation: rms_cur arguments swapped
* improved the alignto command to take additional keyword arguments
which get passed to the used method -> object=aln supported now
* remove _PYMOL_MODULE constant
* fix LITERAL mode command parsing: ignore leading whitespace
