Add support for FunctionCalls and Assignment Expressions
Copy LexerTest function to ParserTest

This should be refactored but works for now. Currently testParserGood5
and testParserGood3 are failing. (Successful testParserBad tests are not
very meaningful). testParserGood3 fails because of unary expressions
that are not parsed correctly. testParserGood5 uses Array Indexes.