This adds support for dynamically loaded plugins at runtime, which
can expose their own protocols or extensions transparently.
With these changes lwsws defaults to OFF in cmake, and if enabled it
automatically enables plugins and libuv support.
Signed-off-by: Andy Green <andy@warmcat.com>
Move install into external shell script. We cannot use apt-get on OSX, use brew instead... Also valgrind isn't used at the moment so skip intalling it.