Add repository creation operation to IVersionControl, implement for hg
and git, add convenience slot with prompts to VCSBasePlugin.
Add respective menu options and make menus are visible in case no VCS is
active.
Change project wizards extension page to list VCS that are capable of
repository creation in a QComboBox in case the directory is not managed
by another VCS (in which case it lists that one for operation 'add').
On that occasion, polish the Project selection to use a QComboBox as
well and add some smartness to find the most suitable project to add via
path matching.
* Use id() for methods returning a string used to represent
some type of object.
* Use displayName() for strings that are meant to be user
visible.
* Quieten some warnings while touching the files anyway.
* Move Factories to their products in the plugins where that
was not done before.
Reviewed-by: dt
