topics: list only topic names in quiet mode This will be helpful in bash completion.

topics: take logic to parse username to a separate function In next patch we will be adding support to `hg stack` to show users, and this logic will be required there too. So let's take it out in a separate function.

changelog: fix a typo in the changelog There is probably many others but that one is fixed now.

caches: switch to 'auto' warming by default This options seems good let us make it the default.

caches: add a 'auto' option for obshashrange cache warming This option will only warm the cache when used as a server.

caches: extract some config reading in 'shouldwarmcache'

caches: pass the transaction to the "shouldwarncache" logic This will allow to have smarter mode about cache warming (eg: only warm them for server transaction.

caches: record 'desc' attribute on transaction This is useful to know if a transaction if server side or not.

caches: protect against missing connection If the connection cannot be established, we should not try to use it.

evolve: don't show working directory obsolete message if we were on it This patch tweaks showing wc obsolete message functionality to not show the message if the operation led us to the same changeset we were on before and it didn't obsoleted it. This make failed updates, update on current changeset and a pull with no change omit showing the message. This has some cons like if you are on rev 1 which is obsolete and you do `hg up <revset>` where revset is some revset which resolves to the rev 1, we won't show the warning as shown earlier.

prev: jump to parent's successor if parent is obsolete and topic is involved `hg stack` shows a linear chain of commits even when they are not linear chain and some changesets are obsoleted and have successors as separate head. This is very nice to have a post evolution view of the stack. However when `hg prev` is run on an unstable changeset whose parent is obsolete and does not topic but parents successor has the topic, it shows no parent on the topic. This patch makes `hg prev` update to parent's successor and make things follow the stack order.

tests: add a test showing wrong behaviour doing `hg prev` on orphan cset If there is an unstable changeset in the topic stack, whose parent is not a part of stack but has a successor which is part of stack, hg stack does shows them in linear order, but `hg prev` on that orphan changset says no parent on that topic. However it should update to the successor of the changeset. It will be fixed in the next patch.