fix major bugs in Find and Search in Project functionality.

fix case sensitive and regexp search, remove duplicating code

Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>

<?xml version='1.0' encoding='utf-8'?>
<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="0" Name="py_ext_0"/>