CHANGES, Docs, version bump, and other miscellany for branching RB-1.2.
LN
OSL Docs

Some updates for the docs, chapter 7.10:
* Removed closures which are not available anymore (orennayar,
cooktorrance)
* Added basic structs (closure header + arguments) for the closures
which have not been mentioned previously.
* Some small fixes.
cmake fix for LDL issue.
Fix for bad LLVM_LIBRARY list generation. This was using "llvm-config --libs", which is overly complicated to transform into actual file list. Instead now it uses "llvm-config --libfiles" which already contains actual full file paths, just needs to replace spaces with semicolons then.
Added build options for static libraries. These are copied from OIIO cmake files to have some consistency.

* LINKSTATIC: Try to use static external libraries when possible. This is not used currently.
* BUILDSTATIC: Build static OSL libraries.
Added a WITH_TESTS option to cmake, which allows disabling all the test shaders and modules. These tests are quite prone to breaking and can be tedious to fix, so this allows getting working OSL builds without messing up the cmake files by commenting out code.
Fix for WITH_TESTS option: Excluding the shaders directory completely is too much, at least the OSL header files are required in the installation files.
Use the existing BUILD_TESTING flag instead of our own extra WITH_TESTS option.
Exclude the TESTSUITE macro when test building is disabled.
Don't include cpp files from liboslcomp when building liboslexec, this would lead to undefined symbols.
Added build options for static libraries. These are copied from OIIO cmake files to have some consistency.

* LINKSTATIC: Try to use static external libraries when possible. This is not used currently.
* BUILDSTATIC: Build static OSL libraries.
Added a WITH_TESTS option to cmake, which allows disabling all the test shaders and modules. These tests are quite prone to breaking and can be tedious to fix, so this allows getting working OSL builds without messing up the cmake files by commenting out code.
Fix for WITH_TESTS option: Excluding the shaders directory completely is too much, at least the OSL header files are required in the installation files.
Add ShadingSystem.LoadMemoryShader function to load a shader with OSO data
directly from a memory buffer, rather than from a file.
update cmake to build on FreeBSD
Add path to standard shaders so it is always searched
Fix FreeBSD compilation issues
Hacks to get Windows building.
More windows build fixes.