Pyknp-eventgraph

Changed
- Represented arguments by a dictionary of **list** of argument information.

Removed
- Removed the attribute `event_head` from `Argument`.
- Removed the parameters `logging_level` and `logger` to `EventGraph.build()`, `EventGraph.load()`, and `EventGraphVisualizer.make_image()`.

Fixed
- Fixed a bug in normalizing event strings.
- Fixed a bug in handling parallel phrases.

Changed
- Improved efficiency and readability of codes.

Added
- Introduced `__iter__()` into the class `Event`. This function yields constituent basic phrases in order.

Changed
- Removed the attribute `omitted_case` from `BasicPhrase`. Instead, introduced the attributes `case` and `is_omitted`.

Added
- Introduced the class `BasicPhrase`, which is a wrapper of `pyknp.Tag`. With this change, removed the class `Content`.
- Introduced the parameters `logging_level` and `logger` to `EventGraph.build()`, `EventGraph.load()`, and `EventGraphVisualizer.make_image()`. According to this change, removed the attribute `verbose` from them.
- Introduced a function to save EventGraph as a binary file. According to this change, removed `EventGraph.output_json()`.

Changed
- Improved normalization rules for an event surface
- Quarried `Features` class from `event.py`.
- Revised the naming of the following functions:
- `EventGraph.output_json()` -> `EventGraph.save()`
- Revised the naming of the following attributes:
- rep -> reps
- rep_with_mark -> reps_with_mark
- normalized_rep -> normalized_reps
- normalized_rep_with_mark -> normalized_reps_with_mark
- standard_rep -> standard_reps
- content_reps -> content_rep_list
- clausal_modifier_event_ids -> adnominal_event_ids
- complementizer_event_ids -> sentential_complement_event_ids
- feature -> features