fix: make cscope

Pkg-config drawback is that it does not allow to distinguish between
CFLAGS (like -pthread) and CPPFLAGS (like -I/usr/local/include).
We want CPPFLAGS for cscope but not CFLAGS. This patch attempts to filter
out non CPPFLAGS words from CFLAGS using the few available gnu make
function :-/
new: boilerplate code for a new statefull parser "TLS"
new: decode TLS records
new: save some cryptographic material from TLS handshake
WIP: decode master secret
chg: decrypt the records.

First HTTPS socket decrypted successfully \o/
WIP
new: small too to convert from guile to ip_addr
new: keyfile management from guile (but still unused)
fix: 2 warnings from guile compiler (among hundreds)
fix: do initiliaze openssl