Add 1.9.3 release notes, bump version number

doc/ReleaseNotes

@@ -1,3 +1,21 @@
+------------------------  RELEASE 1.9.3  ------------------------
+
+This issue fixes several bugs that were still found in 1.9.2.
+
+* 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 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
+* 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
+
 ------------------------  RELEASE 1.9.2  ------------------------
 
 This is a minor bugfix release, fixing a few minor issues that

dtool/PandaVersion.pp

@@ -3,7 +3,7 @@
 // ppremake scripts for Panda.
 
 // Use spaces to separate the major, minor, and sequence numbers here.
-#define PANDA_VERSION 1 9 2
+#define PANDA_VERSION 1 9 3
 
 // This variable will be defined to false in the CVS repository, but
 // scripts that generate source tarballs and/or binary releases for