Update message copy and move functions to allow for custom handling / ignoring of...

Update message copy and move functions to allow for custom handling / ignoring of the error messages.
This fixes a bug where users with exceeded quota's could not login when the filter plugin is actively filtering.

Currently user does not get an error if filtering failed (I am working on it) and it continues parsing the next filter even if fails (I have code for this, but don't think its necessary)

git-svn-id: https://svn.code.sf.net/p/squirrelmail/code/trunk/squirrelmail@9133 7612ce4b-ef26-0410-bec9-ea0150e637f0