Safer and more generic initialization #74
Description
Currently, each curve has a large init function which sets all static values on its instances of the field and group classes to the correct values.
This can be very error prone when adding new curves, or adding new static elements.
One potential solution would be for the field and group classes to have their own static_init functions which accepts all the required static parameters. Missing values could then be identified at compile time, and where there are operations to be carried out (for example to sanity check values?) it can be made generic and shared over all curves.
(Tangentially related to #37)