JsonWizard: Allow enableing/disableing of pages from the Json file

Change-Id: Ic21f0f176f2a82577eaf4a72fbb01c011e1ada2b
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
JsonProjectPage: Pick right directory

Pick the correct directory when the wizard is started via the context
menu of an project node.

Change-Id: Ib2ebba5f796381217673c9030a7b279b6d764a59
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
JsonWizard: Match up files generated by the Cpp Class wizard

Change-Id: I407958b02446e81a449a34519a9eb592723a08a5
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
JsonWizard: Use up-to-date file information

This avoids a new project being opened if you are trying to add a new
subproject to some existing project.

Change-Id: Ic5a2f4b0dedbfd6994c59e4944fc32b11d648871
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
JsonWizard: Replace EmptyProjectWizard with a JsonWizard

Change-Id: Ia199a04b535535722a3b47a9651b16635b019cbf
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
QtVersion: Mark system Qt as autodetectionSource "PATH"

... and use that to retrieve that version again.

This avoids trying to run qmake to make sure it is actually a qmake
and not just some binary with the same name in the PATH.

Change-Id: I7a2c3c85e81c77cc3b56dde088a73e065d03760c
Reviewed-by: Daniel Teske <daniel.teske@digia.com>