Revert "don't even load libraries if too old"

This reverts commit d47aa99c628bcc07e4e8f34e0bbcb91ea4fe1b70.
Revert "remove dired mouse stuff, only turn on tab-complete when on new-enough emacs"

This reverts commit 25b96babae88c6bf6e6292f263f711479695b800.