Added/removed/updated some untracked files.

Finished the complete assignment

Added space in questions.txt.

Added another answer to question 3.

Added questions and code comments.

Source code cleanup.

Added another definition in volume.c.

 - Added last modifications to graphics assignment 7.

 - Part 1 of graphics ass7.

Ignore .o-files in graphics assignment 6.

Graphics include the following assignments:
 - ass1
 - ass2
 - ass4
 - ass6

Operating systems include the following assignments:
 - ass1
 - ass2