fix compilation error

resolves #10

Reviewed-by: Robert Quattlebaum <darco@deepdarc.com>
Fix for weird libedit issue, noticed on OS X.

Related to #10
Fix for some warnings.
Fix contiki build on travis.
Platform abstraction work.
Build fix.
Xcode project cleanup
Allow multicast and loopback addresses to work with V4MAPPED IPv6 addresses.
Make `msg_id` be specific to SMCP instance.
Whitespace cleanup.
Move some `xSEC_PER_xSEC` macros into `smcp-timer.h`
Make SMCP an installable dynamically-linkable library.
Update for travis.
Added `SMCP_LIBRARY_VERSION_CHECK()`.
DTLS teasers