remove urxvt/ext
Squashed 'urxvt/ext/' content from commit 4dec629

git-subtree-dir: urxvt/ext
git-subtree-split: 4dec629b3631297d17855c35be1b723e2d9e7591
Merge commit '32c5ef32fb8b06c6923a7a7d9f37442a727bff0e' as 'urxvt/ext'