This came up in the context of Docker, but it seems it wasn't possible
for hledger-web to serve remote clients directly (without a proxy)
because of 127.0.0.1 being hardcoded ? Now that can be
changed with --host=IPADDR. The default base url also
uses this address, rather than "localhost" being hardcoded.
Also, the --server flag sounded too close in meaning to --host so
I've renamed it to --serve. The old spelling is still accepted,
at least through the next major release I suppose.
Make these modules' names more like the heavily-used types they
define (CliOpts, UIOpts, WebOpts). This is consistent with
RawOptions and ReportOptions, and helps with code navigation.
