Release 5.0.42

• Trace HTTP response even in the case of errors 99e76e. This fixes the long standing issues #297 and #553.
• Added IsConflict helper (#562).
• Added generic IsStatusCode(err interface{}, code int) helper to check for various HTTP status codes being returned from Elasticsearch. The helpers IsNotFound(err), IsTimeout(err) and IsConflict(err) use this helper internally.
• Add ability to fetch the _source of the updated document via FetchSourceContext (957705).
• Updated the Put Mapping API and remove deprecated IgnoreConflicts setting. Added UpdateAllTypes setting (#558 and fecaf7)
• Fix inconsistencies between various range aggregations, using intervals via From and To (dbb16b).
• The Delete API now returns both an error and a response in case of a 404. This reflects what Elasticsearch does (#555 and 801866).
• Prevent issues with terms query and null (see #554 and f98e1f).
• Support reindexing from a remote cluster (487418).
• Add Task Get API.
• Add reindexing in the background via DoAsync. This is different from Do in that it starts a task in Elasticsearch that is watchable via the Task Get API (see #550, 6aa4cc and 3116ec).