new file:   exercises/Foldabletrait.scala
exercise 11.3 (foldable)
exercise 11.2 (monoid)
Merge branch 'foldable'
renamed Typeclasses to FAM
	renamed:    exercises/10.7.scala -> exercises/11.4.scala
	renamed:    exercises/Typeclassesstart.scala -> exercises/FAMtraits.scala