give kimchi a toml config file

[david415]

in the demotools repo we have various kimchi branches we've been using to test with. anyway, we could make one of these have a toml config file to control parameters such as:

• number of clients
• number of mixes
• number of providers
• lambda parameter to exponential distribution for route hop delay sampling

furthermore, kimchi should exit after a message receive test completes. we should make travis run kimchi test mixnet every time we push a git commit to master branch.

[Yawning]

I'm ok with this as long as the current default behavior is preserved. For simple use cases, having to write a config file (or steal one from somewhere) is annoying, and I like the KISS nature of the current behavior. I should be able to run kimchi naked, and end up with a network with > 1 client, listening on a well defined port, with lambda configured to be "not painful" for debugging.

While we're here, there should probably be an option that makes the kimchi state non-volatile (instead of carving out a new temp directory each time).

As a side note, the master branch has no automated tests. The various minclient branches did for a while, but it now spawns mailproxy instances.