Remove unfathomable 2/3 power from CLASSICCHECK().
Merge remote-tracking branch 'origin/development' into feature-remove-twothirds
Tweaking tolerances a couple of tests and a few minor coding style change in classicCheck@chebtech.
Merge remote-tracking branch 'upstream/feature-remove-twothirds' into feature-remove-twothirds
Merge pull request #873 from chebfun/feature-remove-twothirds

Remove unfathomable 2/3 power from CLASSICCHECK().