PR# 17345 Ribbon library missing contract and error handling

The current implementation of the ribbon library is not well contracted, nor do we perform any error handling.

For example, we should have a `exists' and possible `is_destroyed' queries that are used throughout.

The C code often does:

HRESULT hr = S_OK;
if ($a_framework) {
	hr = ((IUIFramework *) $a_framework)->InvalidateUICommand(
		(UINT32) $a_command_id,
		(UI_INVALIDATIONS) $a_flags,
		(PROPERTYKEY *) $a_proper_key);
}

but we never report an error if `a_framework' was Void or if `hr' is not S_OK.

You might end up loosing a lot of time debugging when something goes wrong.