cleanup: removed explicit escape from add_char() and added some comments.

	modified:   editor.rb
cleanup: remove explicit references to escape characters.

Only the Terminal class should know what escape codes are used. For
modularity, all other classes should ask for escape codes and/or escape
regexp's.

	modified:   editor.rb
Directory and doc cleanup

	modified:   LICENSE.txt
	modified:   README.md
	deleted:    TODO.md
	modified:   doc/tutorial.md
	modified:   editor.rb
	deleted:    scripts/LICENSE.txt
	modified:   scripts/config.rb
cleanup: cleaned up a bunch of random stuff

1. greatly simplified write_line() method (needs testing)
  I don't understand why this method was so complex. Which could me
  that I broke it with my simplification.  Time will tell.

2. Simplified syntax coloring code.

3. got rid of unneeded :escape from terminal class

	modified:   editor.rb
feature: can save buffer history to a backup file

History of "saved" text states are written to a backup file, which will
be read in the next time the file is edited.

	modified:   editor.rb
bugfix: proper tab completion in filenames

My previous efforts to clean up the file selector code caused this
behavior to disappear.  This change fixes it, but it is not pretty (a
bunch of code has to be indented).

	modified:   editor.rb
Updated history.

	modified:   HISTORY.md