NO-OP: whitespace

NO-OP: whitespace

- remove trailing whitespace
- remove space after opening brackets and before closing brackets
- add space around operators
- do not use '//' for multi-line comments, do not use "//" on line-start
  to comment-out code breaking indenting (-Wmisleading-indent)
- do add a single space after comment-start /*{SPACE}... or //{SPACE}...
- reserve duplicate whitespace "  " for alignment, remove other duplicate
  whitespace
- use established "TODO" and "XXX" (highlighted keywords)
- remove equal-sign series "====" (those indicate merge conflicts)