Port to python 3
Directory structure refactoring
- directory pylogic with all the sources
- gui files in gui directory
- new entry point script pylogic.py
Clean code
First testing files
Test class Formula and add `__eq__` and `__ne__` methods
Test class Generalization
In Generalization's constructor unify notation for connectives and check the list
Correct tests for Formula's constructor
Add equality functions to Generalization
Test CNF method of Formula
Test CNF method of Generalization and is_literal for top and bottom cases
Fix is_literal for !T and !F. Fix is_alpha and is_beta in formulas with many consecutive not
Check input types in Formula `__init__`
Remove wrong test get_parent_non_literal
Fix is_alpha and is_beta using the their correct definitions
Add get_non_literal_position
Add cnf test for particular cases
Remove unused main
Merge branch 'testing' into dev
Add requirements in travis configuration file