Improve FindRaptor.cmake

	- Is able to look for both raptor1 and raptor2 (raptor2 is default)
	- Handles find_package(Raptor VERSION)
	- If raptor2 is searched and not found but raptor1 is there prints out nice message

Some other small improvements to be more cmake standard compliant.

NOTICE: Untested on windows. Please test if you can.

Could be a candidate for ECM.

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