* add spellchecking
* improve spelling
* improve spelling config
* extend word list
* improve spelling
* improve spelling
* escalate warning in spell check to failure
* fix spelling
* fix spelling
* add plural
* Update doc/spelling_wordlist.txt
* do not stop on warning
* require newest sphinxcontrib spelling
* remove old comment
* add authors as single line entry to spelling list
* reenable stop on warning
