Give BoxContainer a preset capacity to reduce allocations in layout.
Removed Control.GetChild(string) and similar. This was no longer used (and was a pretty bad idea in general), and the implementation had a lot of wasted book keeping to do.
Use UpdateLayout() instead of DoUpdateLayout() in Control minsize changed to avoid doing redundant layout, and by extension style & minsize, updates.
Used RemoveAllChildren instead of DisposeAllChildren in EntitySpawnWindow because it's faster (way less stuff to clear, just let the GC handle it).
Optimized ResourcePath with a better GetHashCode(), better Equals, replacement for List<T>.ToArray()
Fixed enumerator allocations in stylesheet SelectorElement matching to speed up style updates.
ResourceCache now caches fallbacks to avoid constructing Resource instance when fetching fallback explicitly.
ResourceCache now has nested dictionaries for Type -> ResourcePath -> BaseResource storage of resources.
Use calculated property instead of auto property for TextureResource.Fallback
They no longer load system-wide config or user data.
User data is emulated through a VFS.
Also added more hooks to improve the customizability of the test,
for example allowing content to hijack their IoC registrations.
RobustToolbox projects should be named Robust.*
This PR changes the RobustToolbox projects from SS14.* to Robust.*
Updates SS14.* prefixes/namespaces to Robust.*
Updates SpaceStation14.sln to RobustToolbox.sln
Updates MSBUILD/SS14.* to MSBUILD/Robust.*
Updates CSProject and MSBuild references for the above
Updates git_helper.py
Removes Runserver and Runclient as they are unusable
