Creating indexed variables for C++ API and clearing up confusion about C/Python documentation.

[jparsert]

I am missing the ability to create a de-Brujin indexed variable in the C++ api. In python this would be the function Var(index, sort) shown here. After looking at the code it seems to use and be the same as the function z3_mk_bound found in the C API here. When adding this to the c++ API I guess this should be a member function of context (?).

Furthermore,
I find the documentation confusing.
In the python code and documentation the function Var is described to create a free variable used to create quantified formulas. In the C code and documentation the function Z3_mk_bound is described as creating a bound variable. Given that there does not seem to be a big difference between the two functions in C and Python it is a bit confusing why one would create a bound variable and the other a free variable.