Multimaps: I want the guava multimap (<google.git...

# stdlib

[groostav]

Multimaps:

I want the guava multimap (google.github.io/guava/releases/snapshot/api/docs/com/google/common/collect/Multimap.html) in the kotlin standard lib. In my past 3 years on this project I have run into the need for this type at least a half a dozen times.