Added all pre-1975 voting systems

I doubt I'll ever use them, but the incompleteness was annoying me!
There are also some annoyingly-complex changes regarding which countries
used a jury/televoting: see
http://en.wikipedia.org/wiki/Voting_at_the_Eurovision_Song_Contest

Thankfully, everything is consistent from 2009 - present.
Moved common helpers into new file

Things were in CONFIG that shouldn't have been. Now, they are not.
Added notion of counties that have EVER competed

Tweaked the labels and colour scheme accordingly.
Deleted old .txt files that I was using as a reference point, and merged
helpful comments into .js code.