Modified MakeBinOp to no longer produce its name using concatenation and "##".

Doing so prevents emacs tags from working, as well as makes the code extremely
confusing for a newbie.

In the prior state, if someone wants to find the definition of "ExprApp" for
example, a grep through the code reveals nothing. Since the definition could be
hiding in numerous ".h" files, it's really difficult to find. This personally
took me several hours to figure out.