0.6.1: fix: allow sympy.Number to be used as bounds (#35)

* fix: allow sympy.Number to be used as bounds

Both variable and constraint bounds can now be set to sympy.Number types

* test: add a bit more testing

* fix: typo

0.6.0

New gurobi interface

0.6.0b1

Pre-release with experimental gurobi_interface

0.5.0

New interface to scipy's linprog

0.4.2

fix: get rid of stray print statement

0.4.1

Fixes logging in cplex_interface

0.4.0

Low-level API for manipulating objective and constraint coefficients

0.3.3: chore: remove unnecessary excepts

The sympy error is no longer raised. None is returned instead if
expression cannot be converted to a polynomial

0.3.2

Pickling glpk and cplex models is a lot faster now

0.3.1

Small bug fix in cplex_interface leading to problems when changing va…