Release: 0.2.0

Updated to amos 0.2.3, whose loaders
replace the "cases" section of a project's settings. Settings written for
0.1.0 need the changes below.

Added

• Loaders, a genre of amos loaders (CaseLoader) in the new loaders
  module: load_court_listener downloads (if asked), parses, and codes
  CourtListener cases; load_lexis_nexis divides, parses, and codes
  Lexis-Nexis cases; and load_cases loads a table saved by save_cases.
  Named first in the wrangler, a loader makes the project's data, so a
  project needs no item. Loaders work through the project's clerk: sources
  are found (and downloads saved) in its input folder, and a "save"d table is
  kept in its interim folder. The label is checked after the coders run, so
  it can be a column that a coder makes, and the dataset's history records
  the loader and each coder.

Changed

• Requires amos 0.2.3 (and pandas 3).
• courtpy.Project is now amos.Project itself, which runs a workflow with a
  loader without an item.
• code moved to the coders module (it is still courtpy.code).
• The example study and the documentation use sk_logit, scikit-learn's
  logistic regression, because amos 0.2.3 gave the name logit to the
  statsmodels model (which needs pip install amos[statistics]).

Removed

• The "cases" section of a project's settings, courtpy.build,
  courtpy.collect, and the interface module. Move the settings of a
  "cases" section to a "load_court_listener_parameters" (or
  "load_lexis_nexis_parameters") section, add the loader to the start of the
  wrangler's techniques, and rename "folder" to "source". Relative paths are
  now in the clerk's input folder ("save" in its interim folder) rather than
  its root folder.