Werror

I keep going on the '-Werror' cleaning. A lot of signedness problems. I also encounter a lot of 'unused arguments' that I do not know how to fix for all the platforms. I saw that you have added a '-Wunused' flag to the build process, so this must be important, but I do not see how to silent them for all the compilers.

This is just the second patch-set. I will work on the next patch-set once this one will be merge.