Fix `mul` simplification
Remove the `for` loop inside `from_dict`
Add `mul` benchmark
Refactor `Mul::from_dict`
Merge branch 'master' into Fix_Simplification
Remove commented out code
Implement new dict_add_term
Improve readability of code
Remove mul benchmark
Remove empty lines
Use the old `Mul::from_dict` from master
Add a test for `expand`
Change some tests in test_functions.cpp so the tests pass
Replace Mul::dict_add_term by Mul::dict_add_term_new, where possible
Avoid code spanning into two lines
Merge pull request #215 from thilinarmtb/Refactor_dict_add_term

Fix for #212: CSymPy simplification error
Merge branch 'master' of https://github.com/sympy/csympy into pow_simplification
Add new tests, uncomment some of the tests
Update `Pow::is_canonical`