Partial implementation of Android support.
More Android compatibility changes

At this point, I've spent a day trying to get Boost to (very slowly)
compile on Windows/Cygwin. It just built on the first attempt on OS X in
less time than it took Windows to unpack the archive file. I'm going
back to OS X for this one, hence the commit.
Now compiles using NDK release 8e

Doesn't link successfully yet. Apparently I need to do some ranlib
massaging of the ICU libs, at least, to get that working.
Now builds using Android SDK and gcc 4.7
Fixed problems with utfstring, now all platforms will use utf8_cpp unless UTF_USE_ICU is defined (which it isn't, at present). Note that Android still builds in ICU at present, so it's still quite large.
Android build now uses ALooper as the basis of its RunLoop implementation. Pure pthread & condition variable version remains in run_loop_generic.cpp
Merge branch 'feature/NDK' into develop

* feature/NDK:
  Android build now uses ALooper as the basis of its RunLoop implementation. Pure pthread & condition variable version remains in run_loop_generic.cpp
  Fixed problems with utfstring, now all platforms will use utf8_cpp unless UTF_USE_ICU is defined (which it isn't, at present). Note that Android still builds in ICU at present, so it's still quite large.
  Now builds using Android SDK and gcc 4.7
  Now compiles using NDK release 8e
  More Android compatibility changes
  Partial implementation of Android support.