Rendering improvements, Android fixes, and general maintenance.

Our first post-vulkan release with fixes and improvements!

• Here we see SSRL now respecting diffusion of reflecting material's roughness.

Changes in Detail -

• BREAKING: Contour2dDispatcherImSim name fix.
• BREAKING: Now doing screen selection in MMCC like ImSim with boolean parameter and removing DesiredScreen property, thereby resolving #1374.
• BREAKING: Renamed Advancing to TimeAdvancing and Halted to TimeHalted.
• BREAKING: Renamed TimeUpdate concept to TimeAdvance for clarity and consistency with advancing / halted nomenclature.
• BREAKING: Reworked SDL gamepad mapping to use HID-mapped inputs.
• BREAKING: Reduced max cascade shadows to 1 due to their very large memory footprint.
• UX CHANGE: Swapped F10 and F12 in Gaia.
• Made audio master controls configurable.
• Compile fixes with latest F#.
• Fixed fsprojDllFilePaths.
• Fix for allocation failure in windows "Show Desktop" case.
• Decomposed TF code a bit for understandability.
• Reduced render pass splitting on known tile-based targets.
• Bit of semantic clean-up for PixelFormat.
• More explicit note and naming for internal vulkan API references.
• Add ability to don't care about load ops to avoid over-retaining vulkan attachment data.
• Optimized vulkan BufferWrapper to struct.
• Implement vulkan resolve texture workflow.
• Simplified away time advancement / restoration bug.
• Some subtle bug fixes for Transform.
• Now linear filtering when geometry res <> target res, such as in Gaia with inner viewport.
• Fixed vulkan resource leaks on exit.
• Applied roughness-based blur to SSRL.
• Implemented directional shadow fade out.
• Fixed various eye reset regressions.
• Android driver bug workaround for fence waiting.
• Added memory constrained mode to get basic 3D working on more mobile targets.
• Fixed vulkan validation issues on windows.
• Fixed clean up destroyed fluid emitter particles.
• Stabilize Sand Box 2d physics demos
• Update Box2D.NET to 3.1.654.
• Checked in vulkan android validation layer.
• Lowered severity of vulkan errors to aid debugging.
• Fixed (macos): anchor SDL MoltenVK library path
• Fixed (macos): point SDL at Vulkan loader
• Reduced default cost of SSAO.
• Updated Prime to fix delta perf issues.
• Reduced default SSVF steps for lower-end hardware.
• Skipping SSVF convolution process when no lights desire fogging.
• Fixed non-working SSAO resolution divisor.
• SSAO down res by default to save perf.
• Made ray/shao casts not fail in stub physics.
• Always preferring device memory for texture.
• Added missing dispose invocation which led to short-lived leaks.
• Now tracking vulkan image memory usage.
• Revamp vulkan's surface and swapchain architecture to solve Android backgrounding and restoration issues.

Most 2D physics fixes thanks to @Happypig375 and with general assistance for vulkan fixes from @deanjl!

Full Changelog: v20.0.0...v20.1.0