Refactor some methods for finite fields elements.
Basic setup for ellmul spkg.
Use FLINT long types for FF classes.
Use FLINT long types for FF classes.
New ellmul version.
Some fixes for new ellmul and flint structure.
Cleanup unused code and move doctests for finite field elements.
Merge branch 'ticket/17165' into flint_fq_nmod

Conflicts:
	src/sage/rings/finite_rings/element_base.pyx
Merge branch 'flint_fq_nmod' into ffisom
Typo in moved doctest.
Merge branch 'ticket/17165' into flint_fq_nmod
Merge branch 'flint_fq_nmod' into ffisom
Merge back changes from ticket 16930.
New code produce different square root choices for FF elements.
Merge branch 'ticket/17165' into flint_fq_nmod
Merge branch 'flint_fq_nmod' into ffisom