Move cmdtable and reposetup handling out of extensions.py
A new function (extensions.extensions) allows the code that is
interested in those attributes to handle them directly.
This allows some cleanups of extensions.py. Notably, we can
remove the extensions.commandtable hack.
It also makes it easier to add standard extension attributes,
like a "hgwebsetup" function or a "helptable" dict that augments
the data in help.py, etc.
#!/bin/sh
echo 'raise Exception("bit bucket overflow")' > badext.py
abspath=`pwd`/badext.py
echo '[extensions]' >> $HGRCPATH
echo "gpg =" >> $HGRCPATH
echo "hgext.gpg =" >> $HGRCPATH
echo "badext = $abspath" >> $HGRCPATH
hg -q help help