Some updates related to dualspace

[nbouziani]

This PR addresses a few issues related to the recent dual space changes in UFL (#87).

The main changes are:

• Equip BaseForm objects with a coefficients slot.
• Equip BaseForm objects with a ufl_domain as they can be differentiated, which requires inferring the underlying domain.
• Cofunctions now have one argument in the primal space as they map from V to R.
• Coarguments now have two arguments. In fact, Coarguments map from V* to V*, i.e. V* -> V*, or equivalently V* x V -> R, hence they have one argument in the primal space and one in the dual space.
• Add BaseFormCoordinateDerivative and fix the argument analysis for BaseFormDerivative objects.
• Update Action differentiation rule
• Remove support for Adjoint differentiation

(cf. firedrakeproject#39)