[Call-by-name] Handle implicitly cases better

[sureshjoshi]

There are two cases that could probably be handled automatically, if we grab the AST of the called-by-name function:

1. Extraneous implicitly calls - in these cases, where the number of parameters matches the number of arguments the called function expects - we can skip the trailing implicitly entirely.
2. Implicit conversion - if the passed in type isn't the exact one the called function expects, it should be inside the implicitly

Example 1: 23cdef5
Example 2: d137bd6