BRANCH 4.1:
  made keyword mode the default for Keywords search
  made keyword mode search use the AND logic for keywords entered if only a single column is defined.
  increased the search sample to return more unique results in the lookahead suggestions.
  raised a SetupException if the default column set up for Keyword filter search does not exist.
Merge branch '4.1' of https://github.com/Southpaw-TACTIC/TACTIC into 4.1