WIP: trying to make menu more consistent

	modified:   editor.rb
Better menu seems to  work. Needs more testing.

	modified:   editor.rb
search in menu

	modified:   editor.rb
bugfix: editor was crashing if we hadn't saved recently :)

It was trying to compared current state to last saved state, which had
been chopped off to keep undo list from being too long.  I changed from
a linke list to an array.  This presents some challenges with keeping
the saved states indices updated when we prune the history list. But it
still seems cleaner than the linked list.

	modified:   editor.rb
bugfix: buffer class needs to know if undo/redo changed anything.

	modified:   editor.rb
Updated docs

	modified:   HISTORY.md
	modified:   README.md
	modified:   TODO.md
	renamed:    doc/editor.md -> doc/features.md
	modified:   doc/internals.md
	modified:   doc/manual.md
	modified:   doc/tutorial.md
Feature: allow for indentation in line wrapping.

Both justify and linewrap mode will indent the entire paragraph by the
indentation of the first line.

	modified:   editor.rb