Fixed broken tests.
Added a big doc explaining what this class does.
Simplified a function -- yay for tests
Added more docs.
Fixed test.
Created Supertags::cleanMeta and associated test.

Supertag data is always stored as an array, even if the supertag
field only accepts one value. This is so a field can change between
accepting one value and multiple values without needing to migrate
the data.

This is great, but also has one downside -- supertag fields that
only accept one value still output values in arrays. This function
takes care of popping the value out of the array.
Added Supertag cleanMeta function.
Added contentTypes as an unnecessary dependency for instantiating Supertags or Repeater class.
Commented the H-E-double-hockey-sticks out of the repeater class