Separate fit_model

Merge pull request #29 from LAMPSPUC/separate_fit_model_add_format

separate fit_model and add code format

v0.3.0

Update Project.toml

v0.2.1: Merge pull request #24 from LAMPSPUC/export_simulate

Export simulate

v0.2.0

Add simulation feature

v0.1.2: Merge pull request #19 from LAMPSPUC/add_license_version

add license and version

v0.1.1: Merge pull request #17 from LAMPSPUC/fix_estimation_and_paper_tests

fix estimation bug and tests