use the "enter" key to do the search

Just connect the "returnPress" SIGNAL of the search QLineEdit to the "clicked" SIGNAL of the find Button.

Make the search action more smoothly.
:)
Merge pull request #1857 from wsgfz/patch-1

use the "enter" key to do the search
Merge remote-tracking branch 'origin/master' into 0.7.7
Optimized db list retriever
Fixed minor issues
Initial implementation of #1701