Add some stuff to w06: values, valueOf, lift

[bjornregnell]

• methods on enum: values, valueOf

• method on Seq: lift gives option add to slides on Option examples

• perhaps create some exercises if needed

• also ADD lift to quickref

• perhaps also add type Nothing as bottom type (see slide on Any)

[bjornregnell]

Added lift here 8c3fc54

[bjornregnell]

added lift to quickref here 65c78d0