Terminals and non-terminals still need to be quoted, which is a
side-effect of using the Erlang scanner.

Notice that macro names are unquoted atoms.

Update compiler documentation and remove superfluous erlc flags.

The 'dfa_graph' option did not work with Unicode.

The testcase 'unicode' was not correct.

When using Yecc's operator precedence declarations (Right, Nonassoc,
Left), it is possible that some clauses of the generated code are
unreachable. Dialyzer complains, at least if SET_LIMIT in erl_types is
set sufficiently high (to avoid sets of integers to collapse to the
integer() type). Rather than trying to figure out exactly which
clauses are unreachable, Yecc generates a Dialyzer suppression.