New State.set() Functionality

• State.set() now attempts to populate any list encountered in the state that has insufficient length with copies of the relevant provided default value, in order to store the set value at the desired index
• KeyQuery.history now returns a list rather than a tuple, modify at your own risk
• Added and improved code comments
• Added tests for new functionality

This release features breaking changes in the form of modified behaviour in State.set(), and a modified return value in KeyQuery.history.