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.
% init
% no working directory
% setup
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
% hg children at revision 3 (tip)
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
% hg children at nullrev (should be 0 and 3)
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg children at revision 1 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg children at revision 2 (other head)
% hg children -r null
changeset: 0:4df8521a7374
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 3:e2962852269d
tag: tip
parent: -1:000000000000
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: 3
% hg children -r 0
changeset: 1:708c093edef0
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: 1
% hg children -r 1
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
% hg children -r 2
% hg children -r 3
% hg children -r 0 file0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
% hg children -r 1 file0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
% hg children file0 at revision 0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2