Class view: Add drag & drop onto editor splits

Change-Id: I35bc03d4e963500a7edf37d6f9d0ddd0a6c68529
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
QtSupport/OS X: Fix issues with selecting qmake from Qt 4 packages

Native file dialogs can only filter against the names of resolved
symlinks, not the name of the symlink (native Cocoa issue), which is
"qmake-4.8" in case of Qt 4 binary packages.
Simply avoid any stupid issues with not being able to select qmake
executables with whatever prefix by making the filter "qmake*".

Task-number: QTCREATORBUG-13190
Change-Id: Ieb059da75f3f1ecf2a2ff4a3e0633719e54ea43e
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>