v0.19.0

New in this release:

• The client will try to detect whether the gpu supports fp16 and use it if -backend-opts is not used, with parallelism 32 (unless a specific value is given with the -parallelism option).
• The -gpu option selects gpu to use (again if -backend-opts is not given).
• The -run option selects training run on the server.
• -version only shows the client version number (now also shown when starting).
• The next net is downloaded while training, to reduce idle time.