Allow for passing a properties file #20
Description
I've been trying to add some simple docker support for running Proximity. It works currently, but with all the flags you pass, the command line becomes kinda bogged down.
It'd be very neat to be able to simply mount a properties file together with the cards file and the template zip file. Then have the program infer settings from either the properties file or from the command line flags (with flags probably taking precedence)