Getting the #include directives ready for Qt5. This includes the
new-project wizards.

Change-Id: Ia9261f1e8faec06b9285b694d2b7e9a095978d2b
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>

Change-Id: Ic75775473cfb405cee5c53b2dc24144dba51a25c
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@nokia.com>

Make it more consistant with the current plugins:
 * plugin class use the Plugin template instead of Impl
 * add a pluginconstants.h file
 * use the new pluginspec.in file

Merge-request: 216
Reviewed-by: con <qtc-committer@nokia.com>

Reviewed-by: Friedemann Kleint
Task-number: QTCREATORBUG-2655