Revert "make TCP in destiny optional"

This reverts commit 6955a2f7911b9e03b810502d104524a57045a6ca. Though the
general idea makes sense, the implementation should be done in a more
elaborated way.
moved definition of tcp_timer_stack to the correct file
Merge pull request #421 from OlegHahm/revert_tcp_optional

Revert tcp optional