Merge remote-tracking branch 'origin/master'

Merge remote-tracking branch 'origin/master'

* origin/master: (79 commits)
  Platform: check and warn when trying to edit non-project files
  gradient colors for buttons
  initial
  cleanup
  IDEA-121494 (Inspection "method overrides private method" can be improved)
  add table header with sorters
  always use gradient
  diff: fix UnknownFileType detection
  re-arrange downloads label
  github: remove usage of deprecated VcsNotifier API
  [log] IDEA-117553 Optimize details loading: don't parse Changes at once
  134->136
  Cleanup (common method; pointless assertion; formatting)
  nashorn: continue variables presentation simplify V8Scope
  dfa: treat different constants with same values as same (IDEA-121837)
  Rebase feature for update project implemented
  Increment hours in comments
  IDEA-121835 "Breakpoints" UI looks clumsy
  always fold long command line in console (IDEA-121453)
  some CharSequence utility methods
  ...