#65: Removed leading $ from ParameterNode::getName() and setName().
Added more methods to fetch function parameters (#68)
Added isOptional() and isRequired() methods to ParameterNode.
Misc. fixes in #66
Restored ParameterTrait::getParameterAtIndex() using getItem() method of CommaListNode.
Added ParameterNode::getVariable() and requisite assertions to ParserTest.
Merge remote-tracking branch 'origin/master' into parameterName
Fixed dopey bugs in ParameterNode and ParameterTrait.
Merge pull request #66 from grom358/parameterName

#65: Removed leading $ from ParameterNode::getName() and setName(); #68: Added convenience methods to get parameters