Move to Object Oriented data type

Created a datastore object to hold the information for bonuses and stats.
This should make the code easier to understand and maintain (in future).

Implement display(), very rudimentary print out.
Pulls out the datastore.data array and prints it.

Implement subsref(), allowing indexing by ., (), and {}.

Partial implementation of subsasgn(), allowing assignment by ., and (),
but not {}.
Couldn't get that last one working, the parser is expecting a comma seperated list,
outside the the function (subsasgn), and we are working with a matrix.