rearrange main into sections by topic
rearrange main into sections by topic

uucidl/exp.transducers-in-c,uucidl/pre.transducers-in-c,uucidl/exp.transducers-in-c,uucidl/pre.transducers-in-c,uucidl/pre.transducers-in-c,uucidl/exp.transducers-in-c