core: Pass string by reference in FetchFromPortName and DeleteService
Removed common/std_xyz, instead using the std header
loader.cpp: improved file extension checking, made Upper/LowerStr useful

Instead of forcibly taking the last 4 characters, it now finds the last extension separator (the period) and takes a substr of its location.
Added string_util to common, small changes in loader.cpp
Moved common_types::Rect from common to Common namespace