D3D: Implemented context state caching

This avoids most of the redundant API calls.
D3D: Removed cull mode changes for lines and points

Fixed include order and whitespace
D3D: StateManager m_current and m_pending are now value-initialized
D3D: Fixed StateManager member function name case
D3D: Fixed debug validation error

A texture was still being bound when OMSetRenderTargets is called.
State manager resource cache must be flushed to unbind it.
This fixes The Last Story cut scene rendering.
Merge pull request #1503 from kayru/d3d_optimization_cache

D3D: Filter redundant API calls by caching state in StateManager