Need to introduce a quasi-static temporal aspect to elasticity problems. Use the 3rd specification for this and move the other parts of the 3rd spec to a 4th spec. This will need to get tidied up once elasticity is reorganised see #49 .
Move PROBLEM_QUASISTATIC_FINITE_ELASTICITY_SUBTYPE to PROBLEM_FINITE_ELASTICITY_WITH_ACTIVE_SUBTYPE. Change PROBLEM_FINITE_ELASTICITY_CELLML_SUBTYPE to PROBLEM_FINITE_ELASTICITY_WITH_CELLML_SUBTYPE.
Introduce PROBLEM_STATIC_FINITE_ELASTICITY_SUBTYPE, PROBLEM_QUASISTATIC_FINITE_ELASTICITY_SUBTYPE and PROBLEM_DYNAMIC_FINITE_ELASTICITY_SUBTYPE.