+/** @brief Set or remove a value in a @ref kvp
+ * @param kvpp Address of KVP head to modify
+ * @param name Key to search for
+ * @param value New value or NULL to delete
+ * @return 1 if any change was made otherwise 0
+ *
+ * If @p value is not NULL then the first matching key is replaced; if
+ * there was no matching key a new one is added at the end.
+ *
+ * If @p value is NULL then the first matching key is removed.
+ *
+ * If anything actually changes the return value is 1. If no actual
+ * change is made then 0 is returned instead.
+ */