Migrate more functions to xtepan_lib

[jmcourt]

There are a few references to [B_2ms_4B_0_35_H] in FITSGenie due to how special it is. There shouldn't be; its uniqueness should be handled entirely by xtepan_lib. Migrate these functions to xtepan_lib (and create simple twin functions in szkpan_lib as well for compatibility's sake).