[PATCH 0 of 4] keyword: support copy and rename

[Christian Ebert]

Hi,

The first patch of this series is cosmetic and serves the main
purpose that I can understand my own code ;-)

The second patch favors working with contexts.

The third patch removes duplicate search or replace operations
on keyword (un)expansion.

With the 4th patch of this series copy and rename operations
become safer wrt keyword expansion.

Before files containing expanded keywords were copied/renamed
unaltered to a destination ignored by the extension. If these
files were checked in the expanded keywords became
unintentionally part of the change history. I tend to consider
this as a long-standing bug in the extension, which should now be
fixed.

I don't think the wrappery for cmdutil.copy needs to be
write-locked as cmdutil.copy is "called with the repo lock held",
but I'm fine with being taught otherwise.

A crew repo with patch series applied can be found here:
http://www.blacktrash.org/hg-crew-mq/

c