Note that ZMQ_TCP_ACCEPT_FILTER is deprecated
Added AppDynamics as corporate author
Problem: ZMQ_CURVE_SECRETKEY reads beyond end of Z85 data

Solution: change setsockopts on printable keys to expect 41, nor 40
bytes. Code still accepts 40 bytes for compatibility, and copies the
key to a well-terminated string before using it.

Fixes #1148
Reworking Travis script
Minor changes to Travis CI script
Cleaned up test_xpub_nodrop

Renamed test case to actually explain what it's testing, and cleaned up
the code a little.
Merge pull request #1151 from hintjens/master

Documentation patches