Add Insert, Update and Delete writers

This change also adds some type annotations for better type
checking, introduces different write options for writing
transactions and queries, and provides new writeGetFeature and
writeTransaction methods.

src/objectliterals.jsdoc

@@ -595,6 +595,32 @@
  *     calculations.
  */
 
+/**
+ * @typedef {Object} ol.parser.WFSWriteGetFeatureOptions
+ * @property {string} featureNS The namespace URI used for features.
+ * @property {string} featurePrefix The prefix for the feature namespace.
+ * @property {Array.<string>} featureTypes The feature type names.
+ * @property {string|undefined} srsName SRS name. No srsName attribute will be
+ *     set on geometries when this is not provided.
+ * @property {string|undefined} handle Handle.
+ * @property {string|undefined} outputFormat Output format.
+ * @property {Array.<Object>} nativeElements Native elements. Currently not
+ *     supported.
+ * @property {number} maxFeatures Maximum number of features to fetch.
+ */
+
+/**
+ * @typedef {Object} ol.parser.WFSWriteTransactionOptions
+ * @property {string} featureNS The namespace URI used for features.
+ * @property {string} featurePrefix The prefix for the feature namespace.
+ * @property {string} featureType The feature type name.
+ * @property {string|undefined} srsName SRS name. No srsName attribute will be
+ *     set on geometries when this is not provided.
+ * @property {string|undefined} handle Handle.
+ * @property {Array.<Object>} nativeElements Native elements. Currently not
+ *     supported.
+ */
+
 /**
  * @typedef {Object} ol.source.BingMapsOptions
  * @property {string|undefined} culture Culture code. Default is `en-us`.