Skip train when the init model is provided (#116)

At iteration 0, it is not necessary to train the model if a init_model
is provided.

Co-authored-by: Han Wang <wang_han@iapcm.ac.cn>

Add documentation (#79)

* fix bugs of import functions

* fix bug of context

* add example of new input

* new format of submit input. add dargs check.

* command line option for old-style compatibility

* fix s3 config of commands

* add showkey, fix minor issues

* add missing file

* fix bug

* add guidance for dpgen2 command and input scripts.

Co-authored-by: Han Wang <wang_han@iapcm.ac.cn>

show status of workflows (#71)

* show status of workflows.

* fix bugs

* change scheduler converged to complete. add complete for stage_scheduler

* fix == None

Co-authored-by: Han Wang <wang_han@iapcm.ac.cn>

fix RTD installation error (#56)

implement exploration report by BigParameter (#39)

Co-authored-by: Han Wang <wang_han@iapcm.ac.cn>

Pass scheduler as an artifact (#29)

* change interface of scheduler from parameter to artifact

* adjust test for artifact scheduler

Co-authored-by: Han Wang <wang_han@iapcm.ac.cn>

Pub pypi (#20)

* add pub pypi

* remove test pypi

Co-authored-by: Han Wang <wang_han@iapcm.ac.cn>