Updated example (and js code)

A modified version of the multiselectable/multisortable plugins embedded in the HTML 'example' posted by iamvery on 3/16/12. Major change is use of mousedown (not click) to initiate multiselectable, allowing select and drag in one mouse movement. Deselecting an item now requires ctrl/meta click. Additional changes include caching multiple jQuery objects for speed & minification and collating variable declarations.