Having fun making tutorials

[Andrej Mitrovic]

I've added a section on calling conventions and compiling/using
interface files with static libraries. I should also add a section on
using htod and discuss the issue with omf vs coff.

There should be another page for actually using C libraries, although
I think there are some already (there's one in the manual for sure).

After that I'll hopefully write a few things about DLLs, which are
often problematic for newbies.