Remove hsFileStream

It's unused windows-specific garbage.
Fix UnifiedTime collision

Win32's GetCurrentTime and plUnifiedTime::GetCurrentTime collided. Rather
than hacking around the solution by undefining GetCurrentTime, we rename
plUnifiedTime::GetCurrentTime to plUnifiedTime::GetCurrent. This fix is
less fiddly than an undef hack.
Remove global Windows.h include

This is the beginning of efforts to reduce the scope of Windows.h. I have
shuttled it into hsWindows.h (again) and fixed the compilation of the
major apps. There is still some scope work that needs to be done, and the
Max plugin has not yet been addressed.
Fixes some oversights.

Okay, what moron left out the include guards on hsSTLStream.h? Come on,
man.
Remove windoze include from hsThread.h
Be smarter about Pch.[h|cpp] files

As pointed out in #225, Pch.cpp looks suspiciously like a garbage file
when precompiled headers are disabled in cmake. To solve that, I have
changed the precompiled header function to add the Pch source files only
when pch is enabled. This should prevent future accidents.
Smack MaxComponent

This is a huge, complicated project. Therefore, this untangling is not as
comprehensive as the others. It should compile faster and be a little bit
neater, but that's it. Don't expect the headers to look much better!
Untangle MaxConvert

Fix compilation as a result of hsWindows. Also, add precompiled header
support (this shaves off 9 seconds on my machine) and fix some warnings.
As we saw in the PCH-ization of pfPython, includes were untangled (to some
extent) and forward declarations were introduced where appropriate.
Untangle MaxExport
Attempt to de-messify MaxMain

... Similarly to MaxComponent, I'm not sure how much this helps. But, it
(should) compile. I hate 3dsm.
Fix MaxPlasmaLights

The usual--make it compile and add a precompiled header. Also, removed
a few (unused) files of questionable licensing. Check some of the removed
commented out code--it has comments from 1996!
Fix MaxPlasmaMtls
Fix issues from review

- Use lowercase win32 header names for cross-compiling with MinGW
- Correct a unix GUID forward declaration
Merge pull request #238 from Hoikas/hdr-work

More Header Cleanups