Add Package : OpenSceneGraph (#2075)

* Created the initial version of the 'OpenSceneGraph' package.

* Added 'zlib' as a dependency and linked it during the build step.

* Fixed a few minor PEP8 style violations in the 'OpenSceneGraph' package.

* Added cmake as a build dependency and improved the build procedure.

* Made a few important argument updates to improve package compatibility.

* Fixed up a few remaining style issues in the 'openscenegraph' package.

* Added a description for the 'openscenegraph' package.

* Fixed a bug that was causing some 'openscenegraph@3.2.3%gcc' installs to fail.

* Fixed a number of small issues with the 'openscenegraph' package.

* Removed a number of superfluous flags from the 'openscenegraph' install.