Add section weights

Each section has a different weight in the official exam:

001 - Regulations and Policies: Questions = 25
002 - Operating and Procedures: Questions = 9
003 - Station Assembly, Practice and Safety: Questions = 21
004 - Circuit Components: Questions = 6
005 - Basic Electronics and Theory: Questions = 13
006 - Feedlines and Antenna Systems: Questions = 13
007 - Radio Wave Propagation: Questions = 8
008 - Interference and Suppression: Questions = 5

Source: http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01008.html#s5.1

We should use that to give more weight to the most important sections, at least under they are completely drained of questions (assuming bug 1728496 is fixed).