msctf: Starting implementation of ITfContext::RequestEditSession and ITextStoreACPSink::OnLockGranted.

GL_LIMIT - 1 for vertex programs and the GL limit in fragment programs. The
indirect addressing limitation in GLSL applies here as well.

This is the Nth attemt to make clipping work with GLSL shaders. The patch now
uses the GLSL quirk table to handle cards that need a custom varying for
gl_ClipPos, and the code is adapted to the changed state table and shader
backend system.

Since we're using local constants now, we have to update the constants after a
shader change.

This simplifies the loading code a bit. The constants were never
designed to be at the same location in all shaders, so there's no
point in using program.env. This way we don't collide with the d3d
shader constants and its easier to work together with NP2 fixups and
other shaders.

ole32/tests: Show that it's the loword of the separate flag parameter that determines the marshalling context.