Replace Class level variables with metaclass implementations

[Bhargavasomu]

What is wrong?

This snippet of code here is a class level variable and it would be better to define it using a metaclass.

py_ecc/py_ecc/fields/field_elements.py

Lines 197 to 201 in b83b807

	self.FQP_corresponding_FQ_class = type(
	"FQP_corresponding_FQ_class",
	(FQ,),
	{'field_modulus': self.field_modulus}
	)

How can it be fixed

#61 (comment)