Reviewed by: Kai Koehne

 * Fix all warnings about non-explicit constructors except for those
   in 3rdparty code.

Dumping property is too slow and introduces noticable leaks

In order to work, this optimisation needs f7a501515fcf1dafecb88
from Qt.  (else it will not get optimized)

A copy of the client debugging code is made in src/libs/qmljsdebugclient/
(this comes from the qt code from commit 65642dd343bf61)

So the qmljsinspector plugin does not require anymore Qt private headers.