Merge pull request #28 from hurtonm/master

zmtp_channel: More tests
Define CZMQ_EXPORT to ease building

Some existing code that has no other CZMQ dependencies still uses
this macro for its API; defining it is helpful.
Merge pull request #29 from hintjens/master

Define CZMQ_EXPORT to ease building
Revert use of CZMT_EXPORT

Using ZMTP_EXPORT as previously.
Merge pull request #30 from hintjens/master

Revert use of CZMT_EXPORT
Fix pkg-config template

wrong library name and -l option.  In addition, removed the requirements
for zerovm libraries, as they are not strictly required for building or
consuming libzmtp.
Merge pull request #34 from rpedde/pkgconfig

Fix pkg-config template
ipc: Add support for abstract namespace

resolves issue #31