added Argument.type()
reused Argument.type() to shortened some code
added Argument.toString()
added AssignmentList
refactored ArgumentNodesCreator to use AssignmentList
changed names of set Types to contain asterisk
Argument.name() throws exception when it is implicit argument
added Argument.nameSanitized()
name fix in AssignmentListTest
added Param.toPaddedString()
added Argument.toPaddedString()
added AssignmentList.toString()
fixed terminology: 'explicit argument' -> 'named argument', 'implicit argument' -> 'nameless argument'