Added PrefixMap
Added initializer list initialization for PrefixMap
More std container conformant insertion methods for PrefixMap
Trying iterators for PrefixMap...

This doesn't work yet
Added const_iterator for PrefixMap
Removed debug output from PrefixMap
Factored out LazyType
Use PrefixMap and LAZY_TYPE for parsing pan mode
Generate help string for --pan-mode
Use --game-type parameter instead of --ai
Reformat a comment
Factored out TrackCreator
Corrected error in track argument parser.

The objects that create the tracks were created once, but their state
might have changed when the argument was parsed, causing errors when
parsing the second argument. Now only a creator is stored in the map,
and a new object is created when parsing each argument.
Added benchmark mode
Added --printout-frequency parameter
Use boost::algorithm::join for printing population averages
Merge pull request #43 from petersohn/master

Improvements and refactoring