evolve: add a utility fn to check validity of opts passed to `hg evolve`

evolve: don't use graftstate for continuing `hg evolve` Before this patch, if user runs `hg evolve`, we read the evolve state, write a graftstate from that information and run graft command. This patch replaces that logic with new logic which does not depends on the graft state. The new logic is very filtered part of logic from graft command. We did not require a lot of opts checking and filtering revs logic from the graft command as our use case is fixed. This is the start of series/work which will make `hg evolve` better and have a good statefile for itself.

topics: add a new templatekeyword `topic` This patch adds a new templatekeyword topic which can be used to list the topic of the changeset when using commands which supports templating.

packaging: update MANIFEST.in to include new tutorial files I forget to update the MANIFEST.in file when important the new tutorial files. This commit fix that.

test-compat: merge mercurial-4.2 into mercurial-4.1

test-compat: merge mercurial-4.3 into mercurial-4.2

test-compat: merge stable into mercurial-4.3

test: add a test to reproduce issue 5720

test: add missing cycle test Also fix precursors to break on obs markers cycles.

Small typos fixing in the topic tutorial

doc: import the training support Import the training support which was stored in a private-repository before.

branching: merge with stable

evolve: use new trouble names in commit messages There is case when we add trouble to the commit message while using `hg evolve`. This match makes sure, we use the new trouble names. The hash changed because it depends on commit messages.

evolve: use compat.TROUBLES to show troubles in user interface compat.TROUBLES is a dict which contains the trouble name for each trouble according to the hg version user is using. All of the replacements are related to `hg evolve` command.

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.