- lessens open file handles
 - improves help plugin startup further

Task-number: QTCREATORBUG-337
Reviewed-by: ck

Reviewed-by: kh1

Reviewed-by: ossi

Some categories do not have icons yet, unfortunately.

We now do as much as possible lazy initialisation, e.g only start the
full text search indexer if we really access the search widget. Also
moved the QFutur progress into the search widget. Changed all ctors to
be called without an argument, since we share the help engines from
help manager all over the place. Make use of the fact that we only need
to call setupData on the gui engine if we access the help mode, otherwise
all data is fetched thru the core engine whichs setupData is really fast.

Reviewed-by: ck

doing it in 1.3 as well to avoid possible later conflicts

  * 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

Separate category and trCategory and introduce sorting characters
to the categories. Same for id/name.

Add a title label to the pages. Use QGroupBoxes throughout.
Extend SavedAction to work with checkable QGroupBoxes. Polish UI files,
use common layout for VCS plugins. Performance: Apply only visited
settings pages. Add search keywords.

Task-number: QTCREATOR-26

Reviewed-by: kh1

 - show side-by-side if possible
 - always show side-by-side
 - always show full help

The default is "show side-by-side if possible". It's currently considered
possible if the editor is at least 800 pixels wide.

Task-number: 254695

Task-number: 253365