check-code: fix check-code complaint

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.