* render/bgfx: Improved clearing and blending. Added prescale support. Fixes MT07586, MT07587, MT08084.
* render/bgfx: Fixed blend and tint handling. (Fixes Github #1953).
* render/bgfx/blendreader.cpp: Support non-separated blend mode specification for BGFX effects.
* render/bgfx: Reworked how horizontally-padded screen textures are handled. Likely fixes MT08512 and MT08505.
* render/bgfx: Ensure that a texture's width margin is updated in all cases.
* render/d3d/d3dhlsl.cpp: Fixed tinting in HLSL post-processing mode.
* render/d3d/d3dhlsl.cpp: Avoid most redundant state-setting calls. Reduces D3D API calls by about 90% on fruit machine drivers.
* render/d3d/d3dhlsl.cpp: Assign SourceDims and QuadDims uniforms to only those effects that use them.
* machine/laserdsc.cpp: Always add video quad to screen container, adjust tint based on m_videoenable instead.
Made pbobble parent of bublbust, as it seems to be more widespread and
more complete. Also fixed some ROM labels for bublbust.
Made tbyahhoo parent of mtwinbee as the latter has substantial content
removed rather than being localised, making it less complete.
Applied srcclean to JSON files in bgfx subtree.
