hghave: add demandimport checking

hghave: make bzr checks stricter My bzr does not have bzrlib.revisionspec.RevisionSpec, and thus tests were failing because convert refused to believe in bzr, but hghave without this change thought it was available.

help: document wire protocol commands

help: document wire protocol "handshake" protocol There isn't a formal handshake protocol in the wire protocol. But clients almost certainly need to perform particular actions before they can communicate with a server optimally. So document what that is so people understand what's going on at connection establishment time.

help: document wire protocol capabilities All capabilities from the history of the project are now documented.

help: document wire protocol transport protocols The HTTP and SSH transport protocols are documented. This includes how commands and arguments are serialized as well as response types.

help: internals topic for wire protocol The Mercurial wire protocol is under-documented. This includes a lack of source docstrings and comments as well as pages on the official wiki. This patch adds the beginnings of "internals" documentation on the wire protocol. The documentation should have nearly complete coverage on the lower-level parts of the protocol, such as the different transport mechanims, how commands and arguments are sent, capabilities, and, of course, the commands themselves. As part of writing this documentation, I discovered a number of deficiencies in the protocol and bugs in the implementation. I've started sending patches for some of the issues. I hope to send a lot more. This patch starts with the scaffolding for a new internals page.

grep: add formatter support Several fields are renamed to be consistent with the annotate command, which doesn't mean the last call for the name unification [1]. Actually, I'd rather rename line_number to linenumber, linenum, lineno or line, but I want to port the grep command to formatter first. [1]: https://www.mercurial-scm.org/wiki/GenericTemplatingPlan#Dictionary I don't have any better name for the list of matched/unmatched texts, so they are just called as "texts".

grep: build list of all columns regardless of display options These columns should always be available in JSON or template outputs. The "change" column is excluded because it has no useful data unless --all is specified.

grep: build list of columns without "grep." label prefix Prepares for formatter support. We need field names without "grep.".

grep: factor out function that prints matched line with labels Prepares for formatter support.

grep: refactor loop that yields matched text with label As preparation for formatter support, this and the next patch split linestate.__iter__() into two functions, line scanner and displayer. New code uses regexp.search(str, pos) in place of regexp.search(substr), which appears to fix a bug of highlighting.

files: change documentation to match its behaviour (issue5276) Documentation gave the usage pattern as '[OPTION]... [PATTERN]...' when the command match given files as relpaths by default.

templater: add template path to __base__ search This does a fall-back check for style files or directories that are in Mercurial's template path for user convenience. We intentionally don't use this for the built-in coal style because we don't want the style to mysteriously break if the working directory just happens to have a file named "paper".

blackbox: also log alias expansions This should be extremely useful for helping users debug without having to see their complete configuration. Shell aliases do not get their expansion logged, because we don't look and see if we're in a repo before we dive into the execution of a shell alias. As a result, the ui object doesn't know where to log.

test-clonebundles: accept another error string here This is what happens if you run the test in a FreeBSD Jail, rather than "connection refused".