Refs #14319. Widget utilities (on invalidation and selection) that are leveraged by TreeMap but can be leverage by any widget. !strict.
Refs #14319. Fix some styleguide issues. !strict.
fix an issue with Selection.selectItem setter + unit test. !strict.
fixed missing this reference. !strict.
Refs #13101. Fix the most egregious dojox doc errors.

!strict due to existing invalid code.
refs #13101. Get rid of dummy definition for doc parser to understand class inheritance. !strict.
refs #13101. Improve doc. !strict.
refs #13101. More doc patches for some dojox packages. Thanks Michael Billau (IBM, CCLA). !strict.
dojox/widget: api doc formatting fixes, refs #13101 !strict.
numbered list formatting fixes, refs #13101 !strict
add utility mixins into mixins directory and remove dojox references