Add a new shader-versioning infrastructure capable of handling multiple profiles, desktop/ES, many versions, features coming and going in different versions across different profiles, and extensions.

NB: *Use* of this infrastructure is so far only skeletal.

Fixed a few typos and minor issues along the way.


git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@19951 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Todo.txt

@@ -0,0 +1,16 @@
+Minor "to do" items are identified in the source code with "TODO..." comments.
+
+Major items to do:
+
+* Use the new versioning infrastructure to identify all errors specific to
+  - profile
+  - extension
+  - version
+  - stage
+  
+* Add semantics for all new grammar (1.2 through 4.3)
+
+* Replace the preprocessor with a better one.
+
+* Verify/fix thread safety of the parse context.
+