Handle target page correctly. Remove static enumerations
of page ids by member variables to handle differing
page setups. Fix page switching logic in library wizard.

Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>

Task-number: BAUHAUS-396
Reviewed-by: dt

Reviewed-by: Christiaan Janssen

Reviewed-by: Christian Kamm

 * Allow to restrict possible targets in the targetselectionpage
 * Only show the page when it makes sense

Reviewed-by: Friedemann Kleint

Reviewed-by: con

Functionality has been moved back to the plugin for now.

This should allow diffs of the generated file to be more meaningful.

Reviewed-by: Roberto Raggi

Task-number: BAUHAUS-433
Reviewed-by: kkoehne

Fixes: QTCREATORBUG-559

Reviewed-by: kh

After this change and the change we did to 4.7, we are down to ~100ms
time in extensionsInitialized on Windows, should be even more on Linux.

Reviewed-By: Robert Loehning

We need to draw drop indicators for this. I made them
semi transparent white rectangles for now.

Users also can now explicitly set the path to the private
header files by passing "QT_PRIVATE_HEADERS=$PATH" to qmake,
or force qmake to ignore the plugins by passing in an invalid
/empty path.

Reviewed-by: con

Always write "Qt Creator" space. Also, make sure lines are
broken at 80 characters.

Reviewed-by: con

... when creating a new project without any Qt version being
available

breakpoints.

Seems to be needed for "GNU gdb (GDB) SUSE (6.8.91.20090930-2.4)"