- Fixed bug in LM.openFileByName: delete "newHeadline" node after importing
  an external file with sentinels.
- :r and :tabnew commands now use k.getFileName: much simpler and better code.
  :e is probably not needed because r: and tabnew: show completions.
- By default, ignore .pyc and .bin files.
- Fixed crasher when : commands executed via Alt-x instead of colon:  define vc.colon_w in ctor.