Add Sandbox.Filesystem and Sandbox.Compiling
Fix unit tests not finding system assembly refs
Remove AddGameWithPackageBase test - this is no longer supported
Fix hotload fast path not using fast hotload
Cleaning compiler
Filesystem Cleanup
Get rid of ICSharpCompiler, tools can use the Compiler and Microsoft.CodeAnalysis directly
Make editor startup with missing components more unlikely (but not totally fixed)
Embed the framework ref dlls instead of having them loose in bin/ref/
Move compiler tests to Sandbox.Compiling.Test
Lets update the refs while we're here - v7.0.408
Merge pull request #1567 from Facepunch/compiler-project
Moving Compiler to its own project, own unit tests, cleanup. The aim of this is to isolate the compiler and compile group more, so it no longer feels unwieldy. This will also give Tools direct access to CompileGroup and Compiler.