Add some unit tests for collections.Map.
Add some unit tests for collections.Map.

lukecheeseman/ponyta,doublec/ponyc,boemmels/ponyc,Praetonus/ponyc,kulibali/ponyc,Theodus/ponyc,lukecheeseman/ponyta,Perelandric/ponyc,cquinn/ponyc,malthe/ponyc,Praetonus/ponyc,ponylang/ponyc,dipinhora/ponyc,Perelandric/ponyc,Praetonus/ponyc,jemc/ponyc,malthe/ponyc,sgebbie/ponyc,Perelandric/ponyc,mkfifo/ponyc,CausalityLtd/ponyc,Perelandric/ponyc,Perelandric/ponyc,kulibali/ponyc,boemmels/ponyc,cquinn/ponyc,malthe/ponyc,jupvfranco/ponyc,lukecheeseman/ponyta,ponylang/ponyc,doublec/ponyc,Theodus/ponyc,ponylang/ponyc,CausalityLtd/ponyc,sgebbie/ponyc,boemmels/ponyc,jupvfranco/ponyc,cquinn/ponyc,boemmels/ponyc,mkfifo/ponyc,mkfifo/ponyc,ryanai3/ponyc,jemc/ponyc,dipinhora/ponyc,boemmels/ponyc,jupvfranco/ponyc,dipinhora/ponyc,sgebbie/ponyc,sgebbie/ponyc,Theodus/ponyc,Praetonus/ponyc,malthe/ponyc,jupvfranco/ponyc,kulibali/ponyc,ryanai3/ponyc,doublec/ponyc,kulibali/ponyc,Theodus/ponyc,cquinn/ponyc,jemc/ponyc,CausalityLtd/ponyc,mkfifo/ponyc,sgebbie/ponyc,jupvfranco/ponyc,ryanai3/ponyc,mkfifo/ponyc,Theodus/ponyc