ibrcommon: Iterator test added.
ibrcommon: dead unittests removed.
ibrcommon: removed unnecessary code in refcnt_ptr
ibrdtn: Fix set LAST_BIT in Bundle::insert()
ibrdtn: TestSecurityBlock extended

Add mixed usage of authentication/sign with BAB and PIB blocks.
ibrdtn: Block iterator changed to fix issues with STL algorithms

Block iterators returned by Bundle::begin() and Bundle::end() now reference
to block_elem instances instead to Block instances directly. This way issues
with the STL algorithms which copy iterators are solved.