Draft: FT: allow again for large clusters to be decoded

Large clusters in FT are supposed to be transmitted by a pair of clusters, with (size,frac) flags set to (1,1) and (1,0) for the beginning (end), respectively.

However in the data, they always start at (1,0) and end either with (1,0) or (1,1). This behaviour was previously taken as corrupt, and the cluster ignored. However, this arises from a possible miscommunication between the Tell40 and software teams, and will be solved. The clusters are real.

This MR, temporary as it breaks the intended large cluster treatment, allows to still form large clusters.