Check errors don't exist as valid words in the aspell dictionary (#1142)

* Check errors don't exist as valid words in the aspell dictionary

* Install aspell on Travis

* Add some missing packages

* Remove a virtual package

* Just install the version of aspell-python we need

* Keep flake8 happy

* Switch to warnings and count them, so we can see all the aspell errors in one go

* Handle different encoding of the word and aspell

* Try and fix the encoding conversion

* Find out the encoding type

* Don't assert on number of warnings

* Don't record warnings for now

* Warn on all the encoding options

* pprint the encoding

* More warning work

* Use the actual encoding type

* Correct the logic

* ENH: Multi dict support

* FIX: Fixes after merge

* FIX: Better error check

* FIX: More thorough testing, locations

* FIX: Try newer aspell

* FIX: Move to new dict

* FIX: Move

* FIX: Restore removals from #1181

* FIX: One from #1362

* Add rare chack->check, cheque,

* Minor tidy of some dictionary check code

* Add some more suggestions.

* Fix the whitespace

* Really fix the whitespace

* FIX: Refactor requirement

* Log an error when aspell not found and not required

* Fix the error logging

* Test all variants of present and missing from aspell

* Undo some tuple tidying

* Fix the true/false values used

* Skip some flake8 tests

* Fix the test cases

* Correct the not in aspell test and fix some test cases

* Remove a duplicate test

* Use a test word that isn't a typo

* Set the ideal aspell detection logic for each dictionary

I suspect we'll have to relax this as more obscure words won't be in the aspell dictionary

* Be more realistic given the size of the dictionary

* Fix a flake8 error

* Fix another line length error

* FIX: Move

* FIX: Make visible, simplify

Co-authored-by: Eric Larson <larson.eric.d@gmail.com>