check-code: improve quote detection regexp, add tests

Merge with stable

check-code: add a return value to checkfile function The checkfile function returns True if the file is correct, False otherwise.

code-code: Add a logfunc argument to checkfile This helps external tool customisation. The logfunc argument must be a function called to report errors. A new logger class is also added to keep the old behaviour by default.

check-code: Add a ``maxerr`` argument to the ``checkfile`` function check-code.py used to halt after 15 errors. This changeset adds a new argument to the checkfile function to control this limit.

check-code: Add a ``checkfile`` function The part of the code actually checking each file is moved in the ``checkfile`` function to allow external reuses.

check-code: Only call check-code if __name__ = "__main__". This changeset moves the code that actually executes something to the "if __name__ = '__main__'" section to allow the file to be imported as a module.

add a small test for contrib/check-code.py This changeset adds a test file for contrib/check-code.py. This test runs check-code.py against two small files. The first file should not raise any check-code.py error while the second should. A line contains multiple errors to verify the check-code.py behaviour: In the case of multiple errors at the same line, the context line should only be displayed once.

keyword: do not bother about detecting extension path in demo Detecting and showing the path to a keyword extension in a non-standard place only made sense while keyword.py was not shipped with Mercurial. The test output has changed because we do not have a spurious space at eol anymore.

keyword: make kwdemo less verbose 1) Set the branchname always silently with dirstate.setbranch(). We create a branch so that testing the {branches} template does not come up empty. But kwdemo is hardly the place to inform the user by inference why {branches} is empty on the default branch. "demobranch" is ascii and cannot be changed, so using the internal command instead of commands.branch() is safe. 2) Do not show full path to temporary directory (distracting long lines on Mac OS X). 3) No special debug output. Output only related to keyword, no internals like unsetting of commit hooks etc.