* Redefine otEnable/otDisable to just initialize/uninitialize the OpenThread stack.
* Remove otInit API since it is replaced by otEnable.
* Add otInterfaceUp/otInterfaceDown APIs to bring up/down IPv6 interface.
* Add otThreadStart/otThreadStop APIs to start/stop Thread protocol operation.
* Updated NCP implementation to utilize new APIs.
* travis: Do a `make distcheck` instead of just `make check`
Doing a `make distcheck` instead of just a `make check` ensures that
the build system is sane and that the results from `make dist` have
everything needed.
* build-system: Fixes for `make distcheck`
This commit fixes the `distcheck` target by addressing the following
issues:
* Repaired ability to perform builds when the build directory is not
the source directory.
* Addressed an issue with the tarball name that occurs the very
first time `make` is run.