Besides being more clear about what belongs to which, this helps with
docker caching. The server and ui parts are only rebuilt when their
respective subdirectories change.
Extend this a bit further by making the webpack build not depend on
the target architecture. And adding cache dirs so parts of the server
and ui build process can be reused when layer-wide caching fails.
* simplify it. Go from six checked-in config files + one local one to
three checked-in configs + commandline options. I find it less
confusing to have the options plumbed through fewer layers.
* support developing against a https production server, as described in
guide/developing-ui.md.
* fix the source map. The sourceMap parameter in prod.config.js as far
as I can tell evaluated to false when run with production config, and
anyway UglifyJS seems to be incompatible with the specified
cheap-module-source-map. Use source-map instead.
* Various settings in settings-nvr.js module
* settings-nvr-local.js can override settings-nvr.js
* settings-nvr-local is unchecked file
* Both files can be straight maps, or functions returning maps
* webpack env and args available to those functions
