Add various corrections (#1179)

* Add fetchs->fetches and the prefetches variant

* Add extedn->extend and friends

* Add commant->command and friends

* Fix the comments

* Sort the dictionary

* Add laguague->language and friends

* Add assinging->assigning

* Add poligon->polygon and pologon->polygon

* Add plurals of poligon->polygon and pologon->polygon