Add PHP support, but do not include it in the wrapper by default, because
- it doesn't build on Darwin,
- it doubles the closure size,
- there are no official scripts written in PHP,
- it's probably broken: the [example PHP
script](https://weechat.org/files/doc/stable/weechat_scripting.en.html#register_function)
from the manual fails to load.
Enable build-time tests (except on Darwin as they don't build).
Remove `-DENABLE_JAVASCRIPT=OFF`, which was made the default upstream [a long time
ago](340d6646a6).
Add myself as a maintainer.
cea0c62688