Fix case for some calls to @MAPPING object properties.

Closes https://github.com/chebfun/examples/issues/32

It surprising that these weren't breaking any tests. Presumably that means these methods are not being tetsed extensively enough.
Trim some unrequired code.
Set the axis in the correct place.
Update epslevel properly in PLUS() to avoid explosion.
Merge branch 'fix0quantumstates-ylim' into development
Merge remote-tracking branch 'origin/fix-chebtech-plus-epslevel-again' into development