Boolean transpose

• Originally Dyalog APL transposed one bit at a time
• This is very wasteful: we read and write full bytes for each bit
• Jay Foad developed a faster solution for matrices whose dimensions are multiples of 8, but this is a small fraction of matrices
• Dyalog version 16.0 has good performance on all matrices
• Transpose for large matrices is up to 20 times faster!
• This requires some casework…