Introduced a WIP standalone binary tool, "LibsToOso", allowing us to codegen and compile MaterialX libraries, as part as the ongoing work towards a new shader generator, "MaterialXGenOslNodes"

[JoshuaSenouf]

It will build a new executable, MaterialXGenOslNodes_LibsToOso, inside the bin install directory in your install location.
Both the naming of the tool and its install location are likely going to change, obviously.

It can be used like so:

MaterialXGenOslNodes_LibsToOso --outputPath /path/to/my/output/dir --oslCompilerPath /path/to/my/oslc --oslIncludePath /path/to/my/osl/include

This alone will codegen and compile all the MaterialX NodeDef with a valid OSL implementation found in all the libraries in the provided output directory.

The --outputPath, --oslCompilerPath and --oslIncludePath arguments are all mandatory for the tool to work, and they will be checked for both presence and validity (to a degree).

It is also possible to specify a couple of optional arguments, such as:

• --libraries, that allows to specify the comma separated MaterialX libraries we want to process instead of everything, such as stdlib,pbrlib.
• --prefix, that allows adding a prefix to both the filename of a shader, as well as the shader function itself in OSL.

[ld-kerley]

Looks pretty good to me - I think ChrisH will want to drop his shader generator in to the same source/MaterialXGenOslNodes module - and bundle the tool and the new generator together.