Add erc customizations.
Stop tracking ac-comphist.dat
Fix typo in my-sql-dev-connect name.
Remove unused backward-delete-word func.
Add pipes channel to default irc list.
Revert "Remove unused backward-delete-word func."

This reverts commit bf134ff9efecad811d8f1fbb3e96a5b7c7fab74f.
Ignore org-clock-save, bookmarks, elpa dir.