This converts several of the selftests to return a status in their exit code
about whether they 'worked'.
A small bash script framework is added, with a selftest.sh in the mininmal
example dirs that support it, and a ./minimal-examples/selftests.sh script
that can be run from the build dir with no args that discovers and runs all
the selftest.sh scripts underneath.
That is also integrated into travis and the enabled tests must pass now for
travis to pass. Travis does not have a modern libuv so it can't run a
couple of tests which are nulled out if it sees it's running in travis env.
This adds an lws cmake option that builds all the minimal examples as part of lws,
it's useful for QA.
It adds a macro to examples that depend on a particular lws configuration to understand
they should just null out their project definition in builds where the lws configuration
requirement is not met, and we are building as part of lws.
It also adapts all the example library additions to select the just-built-but-not-yet-installed
library in the case it is built as part of lws. If built standalone, it now uses the cmake
platform-abstracted way to add the library requirement too.
