DropJob: don't touch iterator after erasing element

Also drops a redundant condition
Catch exception by reference
Remove dead code

Q_ASSERT(Compiler isn't a total moron);
Servent: Fix IP protocol version distinction

Uwe failed at C&P!
Reduce variable scopes
Remove break after return, it is redundant
Unsigned comparison <= 0 is identical to check for 0
Merge pull request #268 from lorenzhs/misc-fixes

Miscellaneous cppcheck fixes