Cleanup IWizard interface and users

Added 639 lines, removed 1391.

Change-Id: I15ec7dd056d4f7ad79c6dd6a4181007ad14f6a43
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
TaskList: Fix crash

Fix crash when a tasks-file with relative paths is reloaded after
its project was closed.

Change-Id: I3d0b6a3b459e391a3415d765941b2685e601b19f
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Core: Clean up some ICore::instance() uses

Change-Id: I888b30094ed75818ee3af58c94ebf8468afa5eb9
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>