CCCM refactoring / clean-up
Refactoring and cleaning up CCCM related code. CccmModel struct can now carry information about the type of the CCCM represented by the struck. This cleans up especially the IntraPrediction::predIntraCCCM function nicely as there are no more separate branches for all the different CCCM variants available in ECM. Encoding and decoding are bit-exact with the current master.