Parsing_cpp_intro.tex.nw

cf engler article about all the difficulty they had because
had to find how to compile code!!

same with elsa, need to know cpp flags.

Well if do certain tools like refactorer, then partial code,
and have not all library code, and lots of other stuff
that cries for a different kind of approach: parse as is.

sgrep_cpp also requires to parse patterns of code passed on the
command line.