Start removing subdirectory LICENSE files

Moving to a situation where there's only one LICENSE for the whole
distribution.
Add an AUTHORS file

And a script to update it from the git data.
Fix .changed method for bookmarks

Issue #1709
Fix confused test case
Allow multiple bookmarks to be shown at a point

Signed-off-by: Chris Granger <ibdknox@gmail.com>
Revise patch 96400e8fc7a3d7303715d03078350036fc6f6743

Issue #1710
Fix race condition in 5dd408071ccb1200e1b53cfa5cf93b67b8dbd69a
Proof-of-concept: lazy measureLineInner method
fix bug with long unhighlighted lines
attempt to handle marked text
fix linter error
remove debugging information