other: partial migration of network/memory config options from flags (#……2062)This change moves some options to a more appropriate section for the config file. This only deprecates the old options for now, so they're still valid, but we will remove them later (maybe after the next stable release, to give warning).One thing I want to do for the legend position options is maybe expand it, and now is the best time to do so, but for now I'm just copying it over verbatim.The deprecated options will also emit a warning to stderr.This PR also contains a driveby to alias `[network]` to `[network_graph]`.