Added working, but ugly, List
List now implements ArrayLiteralConvertible
List now has Functor instance and some more conveniences
added safeHead and safeTail to List
added test for List Functor
moved Box to Box.swift, renamed safeHead to head
List implements Sequence
Merge branch 'list' of git://github.com/cobbal/swiftz

Conflicts:
	swiftz.xcodeproj/project.pbxproj
	swiftzTests/swiftzTests.swift
Array map tweaks