Try to detect engine by looking at toolchain, executable,
attach mode. Find out path to executable in attach to running
dialog.

Reviewed-by: hjk

Reviewed-By: dt
Task-number: QTCREATORBUG-876

That is e.g. buildSteps() and cleanSteps() --> steps(type)

to update Bauhaus correctly.
Reviewed-by: Lasse Holmstedt <lasse.holmstedt@nokia.com>

... and switch to it in EditorManager::activateEditor.
There no longer is a need for special currentEditorChanged()
handling in the editor that use a special mode.

QmlDesigner receives an additional setting specifying the
desired edit mode. QmlJSEditor detects whether QmlDesigner
is present by checking the registered mimetypes of the
Design mode and retrieves the settings via keys.

Remove some obsolete code and clean up includes
on qmldesignerconstants.h

Reviewed-by: con

Reuse the core help engine in the settings pages. Do not setup the gui
help engine at all since any getter will do so. Split update documentation
into smaller pieces for better performance.

Reviewed-by: ck

Reviewed-by: ck

Reviewed-by: ck

Reviewed-by: ck

Reviewed-by: ck

Reviewed-By: con

Reviewed-by: jbache

Reviewed-by: Daniel Molkentin