added libftdi 1.0 to lib search; added MacPorts search paths
added usual MacPorts install directory to search path
removed headers from list of source files for library; only need to be in INCLUDE_DIRECTORIES()
added found packages include dirs to global list of include dirs; removed 'ansi' flag from GCC flags (not needed in CMake/causes warning in Clang)
changed path for libusb include (now determined for us by CMake)
fixed warnings
- Read_* and Write_* do not need a return value: on failure, we throw an exception in underlying Write()/Read() routines
- fixed 'control reaches end of non-void function' warnings in libftdi impl.
- fixed 'expression result unused' in libftdi impl.