Consider accepting Fortran doubles to MUSICA-Fortran API functions

[mattldawson]

Currently, MUSICA-Fortran API functions expect C types as arguments. e.g., here:

musica/fortran/micm.F90

Lines 247 to 261 in 42f5079

	subroutine solve(this, time_step, temperature, pressure, air_density, num_concentrations, concentrations, &
	num_user_defined_reaction_rates, user_defined_reaction_rates, solver_state, solver_stats, error)
	use musica_util, only: string_t, string_t_c, error_t_c, error_t
	class(micm_t) :: this
	real(c_double), intent(in) :: time_step
	real(c_double), intent(in) :: temperature
	real(c_double), intent(in) :: pressure
	real(c_double), intent(in) :: air_density
	integer(c_int), intent(in) :: num_concentrations
	real(c_double), intent(inout) :: concentrations(*)
	integer(c_int), intent(in) :: num_user_defined_reaction_rates
	real(c_double), intent(inout) :: user_defined_reaction_rates(*)
	type(string_t), intent(out) :: solver_state
	type(solver_stats_t), intent(out) :: solver_stats
	type(error_t), intent(out) :: error

Consider modifying these functions to accept Fortran types (whose kind is defined as a parameter in a shared constants module), and then copying scalars to C types internally and passing arrays as type(c_ptr) instead of, e.g., real(kind=c_double)