Panda3D 1.9.3

This issue fixes several bugs that were still found in 1.9.2.

* Fix crash when using homebrew Python on Mac OS X
* Fix crash when running in Steam on Linux when using OpenAL
* Fix crash using wx/tkinter on Mac as long as want-wx/tk is set
* Fix loading models from 'models' package with models/ prefix
* Fix random crashes in task system
* Fix various race conditions causing threading issues
* Fix memory leaks in BulletTriangleMesh
* Fix loading old models with MovingPart<LMatrix4f>
* Improve performance of CPU vertex animation somewhat
* Show framebuffer properties when fbprop request fails
* Show error instead of crash on use of object before __init__
* Fix hang on exit when using Python task on threaded task chain
* Fix inability to get RGBA renderbuffer in certain cases
* Work around GLSL issue with #pragma and certain Intel drivers
* Improve performance of texture load and store operations
* Fix crashes with pbuffers on Intel cards on Windows
* Support for Autodesk Maya 2016.5
* Add shadow-depth-bits config var to control shadow map depth
* Fix cull issue when rendering cube map (or any multi-lens setup)
* Fix crash rendering with the same camera to different contexts
* Fix compile error when making static build with DX9 renderer
* Fix assertion when using aux render targets in DX9
* Work around Cg bug generating invalid ASM for saturated tex loads
* Fix issues with certain Cg shader inputs in DX9
* Support uint8 index buffers in DX9
* Fix occasional frame lag when loading a big model asynchronously
* Fix interrogate parsing issue with "const static"
* Add back missing libp3pystub.a to Mac OS X SDK
* Fix RAM caching of 2D texture arrays
* Fix Ctrl+C interrupt propagation to runtime applications
* Support for InvSphere, Box and Tube solids in bam2egg
* Preserve "intangible" and "level" collide flags in bam2egg
* Add normalized() method to vectors
* asyncFlattenStrong with inPlace=True caused node to disappear
* Fix asyncFlattenStrong called on nodes without parent
* Fix is_playing() check when playing an animation backwards
* Windows installer no longer clears %PATH% if longer than 1024 chars
* Fix inoperative -tbn/-tbnall/-tbnauto options in egg-optchar
* Fix tinydisplay texture errors on shutdown
* Fix mipmap filtering issues in tinydisplay renderer
* Fix exception when creating intervals before ShowBase is started
* Fix rare X11 .ico cursor bug; also now supports PNG-compressed icons
* Add keyword argument support to make() methods such as Shader.make()
* Fix compilation errors with Bullet 2.84
* Fix exception when trying to pickle NodePathCollection objects
* Fix error when trying to raise vectors to a power
* GLSL: fix error when legacy matrix generator inputs are mat3
* Now tries to preserve refresh rate when switching fullscreen on Windows
* Fix back-to-front sorting when gl-coordinate-system is changed
* Now also compiles on older Linux distros (eg. CentOS 5 / manylinux1)
* get_keyboard_map now includes keys on layouts with special characters
* Fix crash due to incorrect alignment when compiling Eigen with AVX
* Fix crash when writing 16-bit .tif file (now silently downsamples)