Making single parameters to functions also be under EXPR_LIST
Cleaning up type check output
Handling class field accessors (-> and . operators)
Requiring array size be a positive integer upon declaration
Checking size of initializer list against declared array size
Fixing shared memory bug in handle_init_list()

Was not copying the type info, so if any item in the list was a pointer,
all were getting their pointer flag set. Now we explicitly copy the
typeinfo, as it should have been originally.
Handling assignment expressions
Handling binary arithmetic and comparisons
Ensuring left operand of assignment is assignable (i.e. an identifier)

120++ ignores constness.
Handling == and != operators
Handling comparison separately from arithmetic so as to return bool
Handling function return values
Handling unsupported bitwise operators
Handling logical operators
Fixing copied bug in compound type comparisons

Since the || is grouped with a ! on the outside, another ! did not
belong on the right hand side of the ||.
Handling unary + - ! operators
Handling prefix and postfix increment and decrement operators

120++ only allows integer operands to these.
Updating test code for requirements

Classes must use either public, private, or both. Structs without one
may need to be supported.

Pointer arithmetic not allowed in 120++.