# aion 1.7.0
## New classes and methods
* Add `flip()` to permute dimensions of a `TimeSeries`.

# aion 1.6.0
## New classes and methods
* Add `graph_create()` to compute an interval or a stratigraphic graph.
* Add `graph_prune()` to remove redundant relations from a graph.
* Add a `format()` method for `TimeIntervals` objects.
* Add `names()` and `names()<-` methods for `TimeIntervals` objects.
* Add `precedes()`, `preceded_by()`, `meets()`, `met_by()`, `overlaps()`, `overlapped_by()`, `finishes()`, `finished_by()`, `contains()`, `during()` `starts()`, `started_by()` and `equals()` to test for logical relation between time intervals.

# aion 1.5.0
## Enhancements
* The `plot()` method for `TimeIntervals` gained a new `groups` argument.

## Breaking changes
* Remove `as_graph()`.

## Internals
* Use an internal package environment instead of options to set the default calendar.

# aion 1.4.0
## New classes and methods
* Add `as_graph()` to compute an interval graph.
* Add `get_calendar()` and `set_calendar()` to get and set the default calendar.

# aion 1.3.0
## New classes and methods
* Add `calendar_year()` to get the average length of the year of a calendar (in solar days).

## Enhancements
* Improve French translation.

# aion 1.2.0
## Enhancements
* Translate into French.

## Bugfixes & changes
* Remove year zero ticks in plots (Julian calendar).

## Internals
* Epochs of the Gregorian era are no longer represented as subclasses, but as instances of the `GregorianCalendar` class.

# aion 1.1.0
## New classes and methods
* Add support for time intervals.

## Bugfixes & changes
* Fix a bug in `span()`: if a calendar was specified, the result was shifted according to the calendar's epoch (dates were returned instead of durations).

# aion 1.0.4
* Post publication CRAN release.

# aion 1.0.3
* Published in the [*Journal of Open Source Software*](https://doi.org/10.21105/joss.06210).

# aion 1.0.2
## Bugfixes & changes
* Rename the `format` argument of `format()` to `prefix`.

# aion 1.0.1
## Bugfixes & changes
* `plot()` now supports missing values.

# aion 1.0.0

* First release.
