parset-tools collection

[Scott Owens <sowens@cs.utah.edu>]

I have changed the interface of the lexer generator in the parser-tools.

The lex-buf is gone; lexers now take an input-port directly.

The variable lex-buf has been replaced in the actions by a variable 
input-port.

Position structures are now generated with the native port-next-location
function, so line and column numbering must be enabled with the
port-count-lines! function if it is desired.

The get-start-pos, get-end-pos and get-lexeme functions have been replaced
by variables start-pos, end-pos and lexeme.

-Scott Owens