Add agancy->agency and friends (#1727)

* Add agancy->agency and friends

* Add tracsode->transcode and worflow->workflow

* Add @lurch suggestion

* More @lurch suggestions

* Remove ether->either from rare to put it in code

It's the name of a C header file, an abbreviation for Ethernet as used in headers and the name of a Cryptocurrency (although isn't everything nowadays)

* Move ether->either into code dictionary

Due to chemical and programming uses (plus a cryptocurrency)

* Allow dictionary.txt to provide corrections to "errors" in dictionary_code.txt

* Drop ether entirely as it's used for so many things

* Don't allow dictionary to code duplicates again