* update MAX_CAPTION_LENGTH
Telegram silently changed the max length for captions to 1024 chars.
* Update test_constants.py
* change docstrings to reflect new length
* remove message
* clear message and proper match
Should close#400.
* Add parse_entity
* Add parse_entities
* Add MessageEntity types as constants to MessageEntity.
* Add MAX_MESSAGE_ENTITIES to constants.py
Note: the value has been found by experimentation as opposed to extracted from the api docs.
* Add tests for parse_entity and parse_entities