Add SSO state to UI

State for PPOs and SEPARABLE state for Programs now included in the "state" tab on the UI.  Also added some further SSO state tracking and fixed a bug in DRAWABLE state restore code when all drawables are bound to GL_NONE.
Load GL entrypoints on Windows after context creation
Merge pull request #163 from tobin-lunarg/win_ogl_fix

Update GL entrypoints after OGL Context is created on Windows.