Refactoring handling of assignment in parser so that we can support more complex expressions on LHS such as structs of array and arrays of structs.  Currently passes old tests and a couple of new ones.
Refactoring handling of assignment in parser so that we can support more complex expressions on LHS such as structs of array and arrays of structs.  Currently passes old tests and a couple of new ones.

git-svn-id: 4403cc1077de9de61ebbb06aa07b0a825c555f62@2528 dc4e9af1-7f46-4ead-bba6-71afc04862de

blue42u/swift-t,basheersubei/swift-t,swift-lang/swift-t,swift-lang/swift-t,JohnPJenkins/swift-t,swift-lang/swift-t,blue42u/swift-t,blue42u/swift-t,basheersubei/swift-t,JohnPJenkins/swift-t,swift-lang/swift-t,blue42u/swift-t,basheersubei/swift-t,JohnPJenkins/swift-t,basheersubei/swift-t,swift-lang/swift-t,swift-lang/swift-t,blue42u/swift-t,basheersubei/swift-t,basheersubei/swift-t,JohnPJenkins/swift-t,blue42u/swift-t,blue42u/swift-t,swift-lang/swift-t,JohnPJenkins/swift-t,JohnPJenkins/swift-t,JohnPJenkins/swift-t,basheersubei/swift-t