[GL, ES] Added Vector* and Matrix* overloads for GL.[Program]Uniform*

Original request at http://www.opentk.com/node/3584

For the first time, these helper overloads were added through overloads.xml. The rewriter is asking the CLR to create an unmanaged pointer to a managed struct (e.g. `Matrix4*`). This appears to work as expected, but requires more extensive testing.

After merging this PR, the bindings will need to be regenerated.