Introduce a parser_state structure, which describes (most) of the
global parser state. Create such a structure in the entry routines
to the parser and pass it down to the individual functions. The
parser state is initialized and freed with the init_parser_state()
and free_parser_state() functions.
The main benefits are:
1) Isolation of parser state.
2) Keeping the global name space tidy.
3) Prevent memory leaks which could happen in truncated files by
freeing all the parser state after parse.
A somewhat controversial point might be that the individual
parsing functions are split in those that need parser-state and
those that don't. This means that there are now two versions of
the MATCH macro, viz. one for the former and one for the latter.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
