Fix #351 : Added `TwinklesPhoSimCatalogSN` to change output columns
Fix #351 : Added `TwinklesPhoSimCatalogSN` to change output columns

- Define `TwinklesPhoSimCatalogSN` to inherit all properties from `PhoSimCatalogSN`
- Define new getter for `shorterFileName` : This splits sedFilepath on
  `spectra_files/specFile_` and prepends this string to the last element
   of the split list.
- re_assign `self.column_outputs` so that its element `sedFilepath` is
  replaced by `shorterFileName`
	modified:   twinklesCatalogDefs.py

LSSTDESC/Twinkles,DarkEnergyScienceCollaboration/Twinkles,DarkEnergyScienceCollaboration/Twinkles,LSSTDESC/Twinkles