New: zooming on Y axis now is based off the center of the page

-Was top-justified

-Consolidated code from listeners to handleZoom()

-Verified that linking between instances works as well; changed hashParams[y] to make this work
Fixed: various documentation/tests for zoom fix

-Changed jQuery UI references in navigation.js to HTML slider equivalents

-Fixed errors in one test in public.js

-Added documentation/reorganized code in gotoPage

-Added documentation to handleZoom

-Added return value to handleGrid to satisfy linter

-Reorganized getYOffset function

Fixes #202
Fixes #203