Based on PhysicsSolver2 before SSTUPKA's updates, with the following
changes:
Fixed right align of arrows on menu items by using a relative layout and specifying "alignParentRight: true".
Removed third tab items and changed sort by type to sort by topic and sort by topic to sort by chapter.
Added clickability to the pendulum layout and generated a new activity for pendulum problems.
Populated pendulum activity with example picture and working equations solver.