Allow to force the type for a web service search

Some interesting webservice on the internet just give back a value. We should be able to encapsulate the resulting value in a specific type like what is done with copy / paste and drag / drop.
This would allow to encapsulate the result in a mol2d typed object and to display it in a single value module.

Testcase: http://visualizer.epfl.ch/tiny/2VgJtbNXAAo5qT6pHpwx
