Merge remote-tracking branch 'upstream/master' into fix/display

* upstream/master:
  AFNITraitedSpec for Calc
  this is the nth time that I change this...
  test/fixs
  fixing what I messed up
  fixing abspath
  multiple files for tcat and merge
  default suffix more appropriated
  fixing tests accordingly
  use of default_output_type was broken, homogeneizing the inputs/outputs of interfaces, InputMultiPath for Merge and TCat
  adding outfile suffix option to all the interfaces, fixing TCat for it to accept multiple in_files
  Removed unnecessary 'in_file' argument

Author: satra