stratigraphr (development version)

Radiocarbon-related functions (c14_* and cal_*) have been moved to the c14 package. The legacy versions in this package will issue a deprecation warning until the next version, when they will be removed.

stratigraphr 0.3.0

Expanded framework for tidy radiocarbon analysis, adding:
- New S3 object cal, a generic representation of calibrated probability distributions
- Methods for printing and summarising cal objects
- Type conversion functions for cal objects (as_cal.CalDates(), as_cal.oxcAARCalibratedDatesList() and as_cal.BchronCalibratedDates())
- New vignette("tidy_radiocarbon")
Breaking change: cal() and sum() renamed c14_calibrate and c14_sum and now return cal objects.
Breaking changes to stratigraph interface:
- Renamed functions: harris() → strat_connect(), is_valid_harris() → strat_is_valid()
- Removed the notion of a "type" of stratigraph().
- stratigraph() will now return a graph even if it is not stratigraphically valid.
- Renamed vignette("harris") → vignette("stratigraph")
Expanded the stratigraph interface, adding:
- Utility functions for validating stratigraphies: strat_is_mirror()
Fixed read_lst() when reading Stratify 'extended' LST files
Added a NEWS.md file to track changes to the package.

Initial alpha release, including: