Stam

Formal first release of the STAM specification.

Implemented in stam-rust 0.9.0, stam-python 0.4.0, stam-tools 0.4.0.

* Fixes a bug in STAMQL query parser

New features:
* Implemented text validation extension 5
* Support LIMIT keyword in query language (annotation/stam25)

Fixes:
* Preceeds and Succeeds by default allow whitespace in between now (17)

API improvements:
* added methods value() and value_as_str() on iterators over AnnotationData

New features:

* Implemented deletion 3
* Updates to the query language (STAMQL) and engine:
* New `ADD` and `DELETE` statements in STAMQL queries for editing data. Added a method `AnnotationStore.query_mut()` to run such queries that require mutability.
* New `OFFSET`modifier for `RESOURCE` and `ANNOTATION` result types in STAMQL.

Minor API improvements:

* Added conversion of Cursor to usize and isize
* Implemented conversion from std::io::Error for StamError

Miscellaneous:

* Refactored contextvars implementation in query engine
* Updated dependencies

Bugfixes:

* Fixed writing stand-off files
* Added missing implementations in resolving DataKeySelector, AnnotationDataSelector
* In segmentation(), do not include seegments that have no annotations (e.g. milestones)

Fairly minor update release:

New features:

* Added a `segmentation()` method for ResultItem<TextResource> and ResultTextSelection, providing all non-overlapping text segments that together fully cover the resource/text selection
* Generate body IDs in Web Annotation output

Fixes:

* Query: Added DATASET primary constraint for ANNOTATION result type

New features:
* Implemented [STAM Transpose extension](https://github.com/annotation/stam/blob/master/extensions/stam-transpose/README.md): a `transpose()` function is now available on Annotation and TextSelectionSets #28
* Implemented UNION constraint in the STAM Query Language 26
* Exposed functions for ID (re)generation (`IdStrategy`, `generate_id()`, `regenerate_id()`)
* Implemented `TextSelection.intersection()`

Minor API improvements:
* Implemented missing high-level iterator for AnnotationDataSet
* added `Offset.len()`, `Cursor.shift()` and `Offset.shift()`
* added `ResultItem<Annotation>.textselectionsets()`, `ResultItem<Annotation>.textselectionset_in()`
* constrained the characters used in randomly generated IDs to include only alphanumeric ones
* better error feedback in querying
* extra inspection methods for AnnotationBuilder and SelectionBuilder

Bugfixes:
* Fixed serialisation of webannotations and added supported for internal range selectors
* Fixes for merging multiple annotation stores
* Implemented several missing constraint handler for the query language

There was also some refactoring and dependency upgrades.