Released 1.5

This release contains important API changes that may break existing
code.

1. Incompatible change: `Socket.send` series methods are splitted
to `Socket.send` and `Socket.sendMore` and have more overloads for
common message types like string or empty
2. Remove PollItem duplicate API (#11)
3. Fix compiler warning (#10) and compile failure (#12)
4. Add RTReq example from ZMQ Guide Chapter 3

Fix ZmqMsg setData bug; Change license to Apache 2.0; Add mql4-lib de…

…pendences directly

Refactored poll support. Add Chapter 2 examples from the official ZMQ…

… guide.

Fix GlobalHandle bug. Add rebuild method to ZmqMsg.

Add the ability to share a ZMQ context globally in a terminal

README typo fix