Formation Bourrel - 4 couple 319

There are very few dances having a Bourrel that involves 4 couples, and their formations differ in details.  So for the time being we use this Formation as a collective name for all Bourrels involving 4 couples. If their number (ever) grows over a certain size, we can still split it.  Heiko has renamed the Formation to "Bourrel - 4 couple" to indicate that it includes not only one type.

For a discussion on the name see <<https://www.strathspey.org/lists/strathspey%40strathspey.org/t/3047/>>.