added src version of ua
src/ui/collapsingnav: fix call to __parent in init
src/ui/is: added with numeric method
src/ui/DropDown: brought to src from old.  a bit of cleanup and fixes for new practices
src/ui/CollapsingNav: allow for alternative methods for determining if we need to push or pop items from list
src/ui/CollapsingNav: move `handleResize()` to `activate()`
src/ui/CollapsingNav: allow filling list from top or bottom
src/ui/CollapsingNav: pop all from list on deactivate
src/ui/CollapsingNav: reinsert one item if too many are removed from list
src/ui/CollapsingNav: add auto handling of dropdown behavior
src/ui/CollapsingNav: move some `this` to `_this` for compression improvements