bmstore: add handling of the active bookmark This further centralizes the handling of bookmark storage, and will help get some lingering bookmarks business out of localrepo. Right now, this change implies reading of the active bookmark to also imply reading all bookmarks from disk - for users with many many bookmarks this may be a measurable performance hit. In that case, we should migrate bmstore to be able to lazy-read its properties from disk rather than having to eagerly read them, but I decided to avoid doing that to try and avoid some potentially complicated filecache decorator issues. This doesn't move the logic for writing the active bookmark into a transaction, though that is probably the correct next step. Since the API probably needs to morph a little more, I didn't bother marking bookmarks.{activate,deactivate} as deprecated yet.

patchbomb: treat empty address list as no addresses Previously it wasn't possible to use configuration to avoid being prompted for e.g. a CC list when using patchbomb to send emails. We now make it possible to supply an empty value.

config: add hasconfig method and supporting plumbing We add the hasconfig method to make it possible to distinguish between a config value that was never supplied and one that is empty.

verify: replace "output parameters" by return values _verifychangelog() and _verifymanifest() accept dictionaries that they populate. We pass in empty dictionaries, so it's clearer to create them in the functions and return them.

shelve: hook afterresolvedstates

check-code: allow only-whitespace lines in tests These turn out to be necessary to embed diffs with blank lines in test input. So we now complain about whitespace following a character.

check-commit: try to curb bad commit summary keywords The goal of commit summary keywords is to help us sort, categorize, and filter our voluminous commits for our release notes in a way that's helpful and meaningful to end users. Lately, there have been a huge number of "keywords" that are neither words nor particularly key. This patch tries to discourage that by narrowing the allowed characters to alphanumeric. In particular, it doesn't allow "." (method, function names, and file extensions) and "/" (filenames). It also gives a short reminder of what a keyword ought to be.