Task-number: QTCREATORBUG-3752

Reviewed-by: Friedemann Kleint

Merge-request: 229
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>

Provide UI with manual refresh button in BaseCheckoutWizardPage.
Change ProcessCheckoutJob to be able to execute several steps.
Implement in git.

Reviewed-by: Leena Miettinen

  * 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

Introduce new QString id() const-API and sort wizards by
[untranslated] category and id. Introduce respective constants.
Rubber-stamped-by: con <qtc-committer@nokia.com>

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.

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