#740 [IncrementalSearch] fix search history crowding

[Gokul Krishnan]

I'm submitting a patch for a fix / improvement in the IncrementalSearch plugin. The plugin records every keystroke in history, which means typing "TERM" leaves the following entries in search history:

TERM
TER
TE
T

We now try to be a bit smarter by only adding the term to history upon:
leaving focus from the text control
using prev / next / clear buttons or shortcut keys

Discussion thread: http://forums.codeblocks.org/index.php/topic,22828.0.html

[bluehazzard]

Works OK for me