Disabled Unix-centric non necessary include files
Changed some include paths
Removed all printf() I put there and there for debugging.
It builds with the avr32 gcc toolchain, meaning we removed
all the pppd code requiring a unix base.
Using cleaned PolarSSL md4/md5/sha1 implementations, without changing the API,
so that lwIP users already doing SSL or using PolarSSL don't need to compile
md4/md5/sha1 twice.
Added to that, we need a DES library for MSCHAP, and PolarSSL provided
a DES support.
And finally, PolarSSL is outstanding :-)
