Adding windows build infrastructure.
Fixing (read: kludging) the issue where terra.exe would not re-link when terra.lib changed.
Also re-arranged the custom build scripts for LuaJIT a little so it's possible to drop in replacement files.
Merge branch 'master' into windows

Conflicts:
	src/llex.cpp
	src/tcompiler.cpp
removing windows-specific files and fold into single implementation.
Fixing the build to work on Windows again.
All tests pass now.
Added a simple README.
removing spurious printf
Merge branch 'master' into windows
some missing tests.
simplifying main.cpp to make it easier to disable linenoise
indices to pointers/arrays now correctly sign/zero extend.
refactoring indexing for pointer arithmetic to use normal primative casting rules.
Adding support for __unm metamethods. closes #17
fixing typo in precedence table. closes #21.
Fixing bugs that prevented multiple copies of Terra from running on each thread. closes #18

1. global LLVM options/initialization is only done the first time terra_init is called.
2. if multiple calls to terra_init are made, we enable llvm's multi-threading mode.
Merge remote-tracking branch 'upstream/master'