Revert "opentxs: fix -Wtautological-undefined-compare"

This reverts commit 101c9652be73b48fa1f0213470a7fb95c8c3365e.
opentxs: re-fix -Wtautological-undefined-compare
Merge pull request #148 from toxeus/fixWtautological

opentxs: re-fix -Wtautological-undefined-compare
chai: remove obsolete ot_commands.ot
Merge pull request #131 from toxeus/removeChai

chai: remove obsolete ot_commands.ot
Remove const from simple type parameters like bool, int32_t, etc.
Const member functions for opentxs.core
Const member functions for opentxs.core 2
Const member functions for opentxs.core 3