Enabling other plugins to know which tasks currently exist.

As a custom icon is set in most cases anyway.

Reviewed-by: Robert Loehning <robert.loehning@nokia.com>

Task-number: QTCREATORBUG-1790
Reviewed-by: dt
Reviewed-by: mae

Task-number: QTCREATORBUG-1405
Reviewed-by: dt

Thus icons are displayed in a uniform size and don't waste too much space.

Task-number: QTCREATORBUG-1539

Otherwise "rebuilding" the debugging helper doesn't necessarily lead to
Qt Creator picking up the new one (some of the locations can be
read-only).

Reviewed-by: dt

Task-number: QTCREATORBUG-1764

Move open project dialog handling into ProjectExplorer and make it
use its list of project file patterns. Same in Checkout wizards.

Task-number: QTCREATORBUG-1759
Reviewed-by: dt

Reviewed-by: Daniel Molkentin <daniel.molkentin@nokia.com>
Task-number: QTCREATORBUG-1710

Reviewed-By: Robert Loehning

Probably fixes
Task-Nr: QTCREATORBUG-1697

Actually that's not correct, the projectNode() of ProjectNodes is set in
the constructor to "this".
This reverts commit 123e2b6c.

Task-Nr: QTCREATORBUG-1697

Fixes window manager glitches at least on GNOME.

Reviewed-by: dt

Reviewed-by: dt

Task-Nr: QTCREATORBUG-1616

 * Fix displayed shadow build location
 * Fix shadow build location used by newly set up shadow builds

Task-number: QTCREATORBUG-1599
Reviewed-by: dt
(cherry picked from commit 1d8e1760)

On the project page isn't much information for the end user.

Saving another 20%

Is more then twice as fast

Reviewed-By: hunger

Reviewed-by: hjk

I added a second drop shadow to make the panel a bit nicer.
This also makes it clearer what the scrollbar does.

Reviewed-by:thorbjorn

Do the project restore for each project directly after opening and only
then processEvents(). A project might be in a intermediate state between
opening and restoring.

Reviewed-By: Leena Miettinen
Reviewed-By: kh1

Reviewed-By: Leena Miettinen