Update ModuleTest build test to use as many compile warnings as possible. Set -Werror so that any generated warnings produce an error.

Update build test "ModuleTest" to check platform drivers where possible. Add missing copyright/license headers.

Fix UC3 Interrupt Management platform driver not compiling under C++.

Add build tests to verify correct compilation of as many modules as possible under as many architectures as possible.

Fix broken compilation of LUFA under C++ compilers when the Serial peripheral module header file is included in a C++ source file.

Fix missing semicolon in the UC3 architecture host pipe functions.

Fix failed compilation for the XMEGA architecture if USB_DEVICE_ONLY us not specified.