More info from meminfo info, screen scrolling

[Galfurian]

• Now, the /proc/meminfo file also shows the status of the buddy systems for zone ZONE_NORMAL and ZONE_HIGHMEM.
• I've implemented screen scrolling inside the video.c; normally, it's a program that should handle scrolling. But here we have to do with what we have.
• I've moved the RELATIVE_PATH macro to its own file because it was needed in several places.
• I've added a draft for an exercise that asks to build a messaging system with its System Calls. I should try to feed it to an undergrad and see what happens...

That's it, have a lovely coding, you lot.