's all fucked up

It’s really all fucked up! I changed too much of the GeneralField class
so now all the other stuff doesn’t work. In particular, the
GeneralField class’ numerical stuff is all defined in terms of the
integer type still, but Elements don’t have those methods.
Obvious solution: Implement them via operator overloading.
All the same, this is seriously annoying and frankly kind of heart
breaking.