Add references to algorithms, problems, and operators

[abeham]

We should make sure that most of the algorithms, operators, and problems that we include in HeuristicLab from the literature are properly referenced.

We should also discuss if we extend the Item property to store that and further information in (a) separate optional field(s) or if we continue to include it within the description.

A list of algorithms that are not currently referenced:

• ES
• GA
• Island GA
• Island OSGA (we'll have to publish this first)
• LS
• SA
• TS

Also missing is a reference in every Problem that we have.