Implement 'attribute option sets'

[muratcakir]

TBD

Migrated from CodePlex: Issue #328 from muratcakir, on 4/16/2014 4:51:10 PM

[mgesing]

Check whether multiple creation of semicolon separated values (like it's possible with specification attributes) is beneficial after attribute option sets has been implemented.

[muratcakir]

Related to #996