Drops the c/ prefix.
Don't highlight trailing whitespace in eshell.
Squashed 'site-lisp/ace-jump-mode/' content from commit 81c0f3a

git-subtree-dir: site-lisp/ace-jump-mode
git-subtree-split: 81c0f3a66993d21438c07b0505fda3a14b7c9c89
Merge commit '54d2021ecfaf2eae9dfcecd97b6be3a7fad87570' as 'site-lisp/ace-jump-mode'
Adds a variable to configure a custom site-lisp directory.