Document Array types

[aaronsamuel137]

During code review #56, I noticed many JSDoc strings like the following:

   * @param {Array} pendulums - Array of pendulum models.

The PhET convention elsewhere is to document the type of the items in the array, so something like

   * @param {Array.<Pendulum>} pendulums - Array of pendulum models.

[andrey-zelenkov]

Fixed documentation for Array types. Reassign to @aaronsamuel137 for verification.

[aaronsamuel137]

Looks good, closing