Support multiple triggers for a gambit

[IanRogers-LShift]

E.g. what I'd like to do is something like

+ the cat sat
+ the dog ate
+ the flea jumped
+ the cow mooed
- animals are cool

+ *
- I don't think you have that right

there are two workarounds I can see but they're both a bit unhelpful:

+ (the cat sat|the dog ate)
- nice

+ the flea jumped
- {@__respond__}
+ the cow mooed
- {@__respond__}
+ __respond__
- indeed

The first (trigger one|trigger two|..trigger N) seems exactly equivalent to having each trigger on its own line.

NB. yes I know this particular example could be implemented as

+ the ~animal <verb>

but

1. this is just a simplified example and the real problem can't be solved that way
2. it would allow daft combinations like "the cat mooed" which I want to trap