yices_model_set_<type> api in 2.6.4

[ianamason]

Is there a good reason that we did not include the scalar case?

[ianamason]

and double/float too.

[BrunoDutertre]

Probably just an omission.

[ahmed-irfan]

Also add a method called yices_model_set_term that maps a variable to the given term (term_t representing a value) -- as in yices_model_from_map

[ahmed-irfan]

what about yices_model_set_yval? (e.g. yval is taken from some other model)