by passing -A (plus security check).

Task-number:   QTCREATORBUG-503

Task-number: QTCREATORBUG-503

to be used for status/opened output. enabling convenient opening.
Append repository as block data to log text to be able to resolve
relative paths.

Make the diff-base directory a property of VCSBaseEditor and use
everywhere.

Make use of VCS base class.

Add a QVariant cookie to HgTask to be emitted on successful
execution, wired to IVersionControl.

Start the jobrunner on demand, save options only if changed,
give it the structure used elsewhere in the VCS plugins. Remove
last traces of the cmd /c hack.

Do not use "cmd /c hg" on Windows as this will fail randomly
depending on arguments with blanks, such as "-U 8". Output log
messages about synchronous commands, format author correctly,
label menus correctly.

Polish: Canconical slots, const-correctness, some QLatin1Strings/tr,