Build on Linux

[sparr]

I opened #44 to enable dotnet build to find a c++ compiler at all. However, that leaves a lot of hurdles, some easier than others. I'm going to list them here in the hopes that this helps someone make progress in the future.

• fix capitalization for case sensitive #include, such as component.h->Component.h and fileutils.h->Fileutils.h
• Add Linux Platform and necessary conditionals for it (and maybe refactor the conditions into groups so they don't need to repeat)
• Fix whatever is causing gui cpp/h files to be compiled even when specifying -p:Configuration=Debug -p:Platform=x64
• ... or actually port the gui files to use non-windows-specific headers and functions
• Remove ooz dependency on SDKDDKVer.h
• Switch to cross platform equivalents of tchar.h and io.h