ci-travis: build with clang also, and build examples.
Added more known users of librdkafka
Let example logger callback output timestamps
Make rd_kafka_*conf_t structs private, force rd_kafka_*conf_set() API.
WIP: consumer
Fixed formatting in INTRODUCTION
Added rd_atomic_set()
Added a 0.8 consumer
Proper timeouts for produced messages (issue #21)

Timeout msgs regardless of partition (real or UA).
Added testcase for message timeouts.
Finalized configuration property framework.

- rd_kafka_*conf_t structs are now private.
- Use rd_kafka_*conf_set() to populate.
- Each property is now properly documented in CONFIGURE.md (autogenerated)
Termination and refcnt fixes.
Removed 'rk' argument from rd_kafka_err2str()
Topic fixes
Restructured and improved API documentation
Tests now wait for exit properly.
Updated README
Configuration property documentation
Updated configuration API