Automated role management: create "helper roles"

[robstolarz]

Given a channel and a role to inherit properties from (currently just color), helper roles should be created and automatically made pingable.

e.g. !createhelperrole #c-language C should create a "C (helper)" role of the same color as the "C" role and should be made pingable from the #c-language channel.

[telugu-boy]

Good idea, will make deletehelperrole too

[telugu-boy]

https://github.com/strinking/futaba/pull/373