templates: fix missed space between instability labels

templates: introduce labelcset() function in map-cmdline.default as example

templater: load aliases from [templatealias] section in map file This seems sometimes useful as an alias can be a function, but a template fragment can't.

templater: load template fragments from [templates] section in map file This allows us to %include map-cmdline.<style> file in our .hgrc files. The syntax is slightly different as hgrc doesn't support loading an external template file, but map-cmdline files don't use this feature, so the syntax can be considered identical in practice. Unnamed section is remapped for backward compatibility.

config: allow remapping the default section The next patch depends on it. It doesn't make sense that the default section can't be remapped with {'': whatever}.

templater: simplify merge of __base__ dicts by reading it first

phase: add a dedicated pretxnclose-phase hook This new hook mirror the newly introduced 'txnclose-phase' but can abort the transaction.

phase: add a dedicated txnclose-phase hook The new 'txnclose-phase' hook expose the phase movement information stored in 'tr.changes['phases]'. To provide a simple and straightforward hook API to the users, we introduce a new hook called for each revision affected. Since a transaction can affect the phase of multiple changesets, updating the existing 'txnclose' hook to expose that information would be more complex. The data for all moves will not fit in environment variables and iterations over each move would be cumbersome. So the introduction of a new dedicated hook is preferred in this changesets. This does not exclude the addition of the full phase movement information to the existing 'txnclose' in the future to help write more complex hooks.

bookmark: add a dedicated pretxnclose-bookmark hook This new hook mirror the newly introduced 'txnclose-bookmark' but can abort the transaction.

bookmark: add a dedicated txnclose-bookmark hook The new 'txnclose-bookmark' hook expose the bookmark movement information stored in 'tr.changes['bookmarks]'. To provide a simple and straightforward hook API to the users, we introduce a new hook called for each bookmark touched. Since a transaction can affect multiple bookmarks, updating the existing 'txnclose' hook to expose that information would be more complex. The data for all moves might not fit in environment variables and iterations over each move would be cumbersome. So the introduction of a new dedicated hook is preferred in this changeset. This does not exclude the addition to the full bookmark information to the existing 'txnclose' in the future to help write more complex hooks.