create_z3_var_typed shall be used throughout the code

[jlvargasme]

Past prototyping used create_z3_var when the type was unknown and this caused many variables to be assumed "float" type. This is the source of many z3(type error) exceptions.

We should replace all the occurrences of create_z3_var with create_z3_var_typed or any other function that will give the correct type to a z3 variable.

For an example, see the create_base_var_from_pattern function that uses pattern matching in a Zelus pattern construct to figure out base type and variable name.