parser: make parser_set_buf() private

parser: make parser_append() private

constify the parser structs

untangle a bit buffers and parsers Now buffers have a nicer interface, taking explicitly the buffer where they push stuff, and the code that deals with buffers doesn't need to peek into the parsers. The parsers now are 'pure' structs without state attached to them, the state was moved to the buffer.

parser: make parser_foreach_line private while here also inline fn: it's always p->parseline.

move includes back to the root directory Splitting stuff into sub-directories was just a big mistake.