Create a local testnet for fast, private testing

0. Stop all chinilla processes. Check that they have stopped with ps -ef | grep chinilla
1. Create a new chinilla root using export CHINILLA_ROOT="~/.chinilla/my_testnet", then chinilla init. Don't forget to export CHINILLA_ROOT, or prefix your chinilla commands with CHINILLA_ROOT="~/.chinilla/my_testnet" if you want to run on my_testnet when starting a new terminal.
2. Create a new entry in config.yaml with a different GENESIS_CHALLENGE, and reduced DIFFICULTY_CONSTANT_FACTOR. 2^67 constant factor is around 110PiB assuming a fast timelord. So if you have around 110GiB, you can set it to 2 ^ 47. Decrease SUB_SLOT_ITERS_STARTING to something like 2^23 if you are using a slow computer. Decrease PLOT_FILTER if you want to have more proof checks per signage point.
3. Make sure to add my_testnet to all places that need it, like network_overrides.config, and selected_network
4. Change the introducer URLs to point to localhost so you don't contact the real ones
5. Do sh install-timelord.sh
6. Run the system with chinilla start all
7. If you have installed the gui, run (cd chinilla-blockchain-gui && npm run electron &)

You can generate a new genesis challenge by running python, and entering the following commands:

from secrets import token_bytes
print(token_bytes().hex())