This preprocessor is compliant with ANSI C89/ISO C90, except there is
no support for wide-character constants/string literals or trigraphs.

When given the -x flag, C++ mode is enabled; BCPL-style comments
are honored and :: ->* .* are treated as single tokens. This is
sufficient to comply with preprocessing as described in the ARM,
but keyword operators and digraphs from C++98 are not supported.

This code has not been rigorously tested, though it does properly process
the included examples from the Standard. There are doubtless lurking bugs.
No performance tuning has been done, either, and there is certainly room
for improvement here: in particular, a superimposed code should probably
be introduced to reduce the frequency of scans of the macro table.

							- cey 1/1/22