Fix a crash when double-clicking a replay with an unknown map.
Merge pull request #6800 from pchote/fix-replay-browser

Fix a crash when double-clicking a replay with an unknown map.
Add chrome for slider thumb.

update hardcoded references to chrome.yaml to use public parameters.
Merge pull request #6814 from steelphase-forks/bleed-slider-thumb

Add chrome for slider thumb.
Rewrite shp(ts) parsing to avoid offset issues.  Fixes #6822.
Make the legacy editor more robust against invalid templates.
Merge pull request #6824 from pchote/external-editor-templates

Fixes #6812
Merge pull request #6823 from pchote/fix-shpts-offsets

Closes #6020
Dispose of graphics resources deterministically.

Textures, FrameBuffers and VertexBuffers allocated by the Sdl2 Renderer were only being released via finalizers. This could lead to OpenGL out of memory errors since resources may not be cleaned up in a timely manner. To avoid this, IDisposable has been implemented and transitively applied to classes that use these resources.

As a side-effect some static state is no longer static, particularly in Renderer, in order to facilitate this change and just for nicer design in general.

Also dispose some bitmaps.
Clean up style of files affected by the last commit.