merging PAC with TRUE/FALSE or as value

[signeisacson]

In some functions (like PAC_summary), merging with PAC is a true/false vector, whilst in other functions (like add_reanno) you provide the PAC list you want to merge with as a value.
Maybe decide on one way and keep it constant for all functions?

[Danis102]

This is done because some times a PAC object is needed for the function to run, while sometimes it is not. Every function will need some special consideration. All should be explained in the manual for each function. But I will keep this issue open in case we come up with a better alternative.