Updates history log

Adding the read the docs link in readme

Bug fixing: error in local ensemble creation for sources with high nu…

…mber of fields

Adding code review comments and pep8 and pylint cleaning

Adding threshold combination method to MultiModel objects

Version date updated

Adding new version 0.9.1 and history log

Bug fixing: recovering PYTHON_OPERATOR map, erased by mistake

Changing and cleaning code after code review and pep8, pylint

Changing predictions in tests according to the backend split change