Splitdefinitions is wrong in case loops are not binary

[Broes De Cat]

[I currently have a solution through bootstrapping]

Splitdefinitions works by partitioning all rules of a def into different partitions if they define different symbols. Afterwards, it merges 2 such partitions if there is a loop possible among them.

This misses every loop that goes over more than 2 symbols.

a <- b b <- c c <- a

[Bart Bogaerts]

Disabled splitting of definitions

see issue #523

→ <<cset fd7fb682f2b9>>

[Bart Bogaerts]

implemented splitting of definitions through bootstrapping.

Fixes #523

→ <<cset 8dfd853dbac5>>