WIP: Inline docs for libwget

This is work in progress.

Let's see if I can have 50% of the libwget public functions documented by the end of this month!

net.c and net.h will be ready by tomorrow or the day after to the latest, with all the dirty inline TODOs resolved.

Here and there I've also made some minor changes to the code to make it more readable. I know that's very personal but if I made them it's because it really improved readability for me, so please consider it.