Adding a source file for infix parser.
Basic skeleton for infix parsing.
Testing minimal infix parser.
Parsing an infix expression.
Generalizing operator implementations.
Fixig regex matcher.
Parsing expressions with more than one operator.
Handling associativity.
Pre-prefix housekeeping.
Generalizing storage and lookup for operatos.
Handling prefix operators.
Handling associativity better, and pacing the way for handling postfix.
Refactoring operators.
Handling parentheses.