This commit adds support for version and version_type to the Term Vectors API.
This could be useful in the following case whereby the user gets a document
and later wants to generate its TVs. With version, this would ensure that only
the TVs of that particular document are generated, and error out if the
document has been updated in between.
Closes#7480
We speak of the term vectors of a document, where each field has an associated
stored term vector. Since by default we are requesting all the term vectors of
a document, the HTTP request endpoint should rather be called `_termvectors`
instead of `_termvector`. The usage of `_termvector` is now deprecated, as
well as the transport client call to termVector and prepareTermVector.
Closes#8484
Alex Ksikes