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
mkdir r1
cd r1
hg init
mkdir a
echo foo > a/f
hg add a
hg ci -m "a/f == foo"
cd ..
hg clone r1 r2
cd r2
hg mv a b
echo foo1 > b/f
hg ci -m" a -> b, b/f == foo1"
cd ..
cd r1
mkdir a/aa
echo bar > a/aa/g
hg add a/aa
hg ci -m "a/aa/g"
hg pull ../r2
hg merge
hg st -C