Sequence and Rvalue syntax ambiguities

[phorward]

There are several conflicting ambiguities in the syntax of Sequence and Rvalue which result in undesired results.

• list() (1, 2) is interpreted as call to list, who's result is called with 1 and 2. Desired result is a list() followed by a list 1, 2.
• list().len(). is interpreted as list().len() and the "any character" Token identified as .. This syntax should generally prohibited, allowed should only be list().len() . with a delimiting whitespace in between.

[phorward]

This intersects with #43 and #45.