Added EllerBuilder, but still struggling with implementation.
Added another representation for unions - as vectors. Still got problems with the right wall of the first cell.
Removed a silly test line that were completely forgotten.
Work-in-progress commit made before switching to unordered_set for unions.
Switched to unordered_set from vector when dealing with unions. So far, so good. Though, maybe you can call some aspects of generation less 'random' now. To minor to deal with at the moment.
Almost done - it is only matter of adding proper last line handling now.
Added the code for the last line adjustment and there you go :) Though, there are an error somewhere in the algorithm - there are occasional loops.