Use m` in operator-pending mapping

Apparently I was wrong about being unable to call m` in an
operator-pending mode mapping.
Remove -bang from DEFPLUG
Revert "Only set pcmark on first visual motion"

This reverts commit 2c198bf17117011364d90337c1467088719a45ef.
Add nojump flag to defplug

We do this so we don't set the jump mark on element-wise movement.
Builtin w, e, ge, and b don't set the jump mark.
Don't use the bitwise functions in defplug

These were not introduced until 7.3.377, and we would like backwards
compatibility to 7.3 release.
Fix empty('<bang>') repeat logic
Remove curwin->w_curswant hack

Looks like this was a temporary bug in the version of Vim I was running
at the time.
Update documentation with requirements

We are now targeting full 7.3 compat