Update copyright year to 2016
rtree.el: Use American spelling for 'normalize'
Update copyright year to 2015
Update copyright year to 2014
Update copyright notices for 2013
Add 2012 to FSF copyright years for Emacs files.
Convert consecutive FSF copyright years to ranges.
Update copyright years.
mm-extern.el (message-goto-body): Update declaration.
Implement rtree-length.
Fix typo.
Implement rtree-delq.
Start rtree-delq.
Make code slightly faster.
Implement rtree-add.
Rewrite rtree-memq as a non-recursive function.
Simplify rtree-extract.
Reimplement extraction as O(n).
Implement rtree-extract.
rtree.el: New file to handle range trees.