Extend shaders support

**Original report ([archived issue](https://osrf-migration.github.io/ignition-gh-pages/#!/ignitionrobotics/ign-rendering/issues/24)) by Ian Chen (Bitbucket: [Ian Chen](https://bitbucket.org/%7Beaa6fca5-6deb-43f6-907f-971c144735dd%7D/), GitHub: [iche033](https://github.com/iche033)).**

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from comment in [pull request #55](https://osrf-migration.github.io/ignition-gh-pages/#!/ignitionrobotics/ign-rendering/pull-requests/55):

* While the ShaderParam currently encodes INT and FLOAT, it should probably be expanded to cover other commonly-used types with more than one value (Vector2, Vector3, Vector4, Matrix33, Matrix44)

* It may be useful to port the capabilities/features framework from ign-physics to the rendering system to indicate that some renderers don't support raw shaders (eg Optix):
* ign-physics Feature (wip): https://github.com/ignitionrobotics/ign-physics/blob/e021b8d438af314c4862d757cb0719965578457b/include/ignition/physics/Feature.hh
* Checking with OGRE: https://www.ogre3d.org/docs/api/1.9/class_ogre_1_1_render_system_capabilities.html

* Potentially expand for other shader types: Geometry, Compute, Tesselation