Add support for recording and replaying matches

[dzrw]

This patch adds support for recording matches (start --capture) and replaying recorded matches (replay replays/last-match.yml). Matches are recorded as bot-independent YAML files, so that you can share replays without necessarily sharing the bots that participated.

Caveats

The current match is always saved in replays/last-match.yml, use the command line to rename files that you don't want overwritten. If someone wants to improve this, it should be relatively simple.

The replay files get a little large (1.5Mb, 2 bots, 3000 ticks) because I'm using YAML instead of a binary format. If someone wants to swap the format to improve file sizes, it should be relatively simple.

The configuration file is not included in the recording because it was a bit too much work to monkey-patch over a different configuration, so matches should only be replayed on installations sharing the same configuration. In practice, this means bundling a recorded match along with its configuration.rb file.