system: Add basic WinPathAbs() and PosixPathAbs() for MSYS
make: Fix typos in EncodeWord() and DecodeWord()
Factor out graphviz module
graphviz: Don't bother with _ROOT or _BIN if _DOT is in the path
doxygen: On Windows, look for doxygen in Program Files if it's not on the path
runnable: Rename ArgPath() -> ArgPathFragment() and ArgPathAbs() -> ArgPath()
system: Rename WinPath() -> WinPathFragment() and WinPathAbs() -> WinPath()
system: Add WinPathOnWin()
doxygen: Configure and run correctly on Windows