Qbs: Rewire handling of parsingStateChanged slot

Change-Id: Ieba22469249ba86b28d098e59fe7e953033243c9
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Qbs: Remove activeTargetChanged slot

Changing the build configuration triggers a reparsing of Qbs nowadays,
so that is update is already covered.

Change-Id: I8415fe8e1da71e2c7b044cbf7623362b6cdf4ed3
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Qbs: Make reparseQbs act on the startup project

This was just plain wrong before...

Add m_currentProject, keep it up-to-date and use it for the reparse Qbs
action. Trigger update on the action when appropriate.

Change-Id: I6d9d82d5c5fbdfbd5d28690e16587c66e5c13d06
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Qbs: Split updateContextActions

... into a part that actually updates the context actions and a part
that does the setup of the internal state.

Change-Id: If6b90df98d56b1546e3d0211998d027db27fdf1d
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Qbs: Fix updateContextActions

Take parsing state into account.

Change-Id: I8b6d7b1d1fc7b9fb61a22cf251ff171a0c3dde1f
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Qbs: Turn private update* slots on QbsPMP private methods

Change-Id: I1b25d09d51fb3e55257129221e792da92c8e51bf
Reviewed-by: Daniel Teske <daniel.teske@digia.com>