Moved implementation of OutsideTestRunnerUTest::instance() outside of class definition.

Would resolve to multiple copies of _instance otherwise with cl2000.
cl2000-specific git ignores.
Base include folder should be "cpputest/include", as it is for all other headers.
Added extern "C" declaration around C header inclusions. Added explicit casts to C function types for function pointers.
Correct location of sim28335.cmd.
Moved AllTests.cpp for embedded systems (hardcoded command line arguments) into tests/Platforms and restored original files.