Add Lookup, a serializable alternative to ILookup<string, string>.
Replace usages of ILookup<string, string> with Lookup.
ExecutionProxy receives a Lookup instead of command line argument string[].
Avoid wasteful reparsing of command line arguments now that all such parsing happens on one side of the AppDomain boundary.
Move CommandLineParser from Fixie to Fixie.Console, the only place it is now used.
Move CommandLineOption from Fixie to Fixie.Console, the only place it is now used.
Merge pull request #67 from plioi/SimplifyCommandLineArgumentUsages

Simplify command line argument usages