v0.5 update

It's been a close to two years since working on this! I thought of making the rolls default to d4 unless you have a relevant move (like my other 24XX game Poco), but I think the current default d6 works -- with moves starting at d8, it's only two steps to improve to d12, which triggers evolution, which is a fun thing in Pokemon/Digimon stories. 

Changelog:

• Harm: simplified injuries to two scales, lesser injuries take a night's rest to heal and severe injuries take a week or a healing centre visit.
• Defence: changed defence to making a single mark to bump up the overall toughness of etymons, as well as the option to mark items for humans (since we love collecting all this junk anyway). The implied increased toughness of etymons would explain why they're doing more than the fragile humans! 
• Mentioned that you earn more credits by helping someone in need (instead of winning battles, as in Pokemon).
• Various minor clarifications