* Add multiprocessing Pool and create function for single cutoff forecast
* add params to single forecast function
* Add iterable for input params for pool
* Add docstring for single cutoff forecast func
* Add check for multiprocessing in test_cross_validation
* check ofr is None and is True and add better description for multiprocess in docstring
* Raise error if wrong args chosen and add test
* fix conflicts
* Change arg to True/False, model.kwargs
* docstring units and few more fixes
* change to iterator and add back tqdm to for loop
* add option in diagnosics notebook about multiprocessing option
* add extra test for checking calls to single forecast func
* Added feature to mask seasonality
* Added conditional seasonality tests and fixed plotting it
* Fixed diagnostics for conditional seasonality and cleaned up code
* Allow both both hoidays and append holidays
Match holidays in predict and fit
Add test for append_holiday features; minor fixes
Add column name validation for append_holidays names; allow only one country
Fix bug about holiday year different from input year and also other bugs
Change function description
Add append holiday feature for R
* Add test for R/Pyrhon; fix bugs
* Update memory requirement description per #326
* Fix R warning with extra regressor; disallow constant extra regressors.
* Fix unit test broken in new pandas
* Fix diagnostics unit tests for new pandas
* Fix copy with extra seasonalities / regressors Py
* Fix copy with extra seasonalities / regressors R
* Fix weekly_start and yearly_start in R plot_components
* Fix plotting in pandas 0.21 by using pydatetime instead of numpy
* Version bump
* Update README for new version
* Fix missing columns in SHF with extra regressor
* Update memory requirement description per #326
* Fix R warning with extra regressor; disallow constant extra regressors.
* Fix unit test broken in new pandas
* Fix diagnostics unit tests for new pandas
* Fix copy with extra seasonalities / regressors Py
* Fix copy with extra seasonalities / regressors R
* Fix weekly_start and yearly_start in R plot_components
* Fix plotting in pandas 0.21 by using pydatetime instead of numpy
* Resolve conflict
* Change comments and add error column to output DataFrame
* Change file structure
* Update
* Modified diagnostics
* Update diagnostics.py following the advice on Github
* Add tests and documentation
* Change copy method into Prophet class and reflect comments
