style: make style hook work with pre-qrefresh and update to use new code

style: make style hook work with pre-qrefresh and update to use new code
clean up the code a little bit while we're at it.

I recommend that everyone adds the pre-qrefresh hook below since it
will make qref run the style hook and not just commit/qpush

[extensions]
style = <m5 path>/util/style.py

[hooks]
pretxncommit.style = python:style.check_whitespace
pre-qrefresh.style = python:style.check_whitespace