Fasta: make exception-ful API the default
setup.ml: remove on distclean and ignore
Lines: new module to replace Transform.Line_oriented
copy contents of Transform.Line_oriented to Lines

Mostly a verbatim copy, but slight restructuring and renaming.
Lines: move some items under new sub-module Transform
Lines: enforce stronger item type
Lines.Buffer: rename parsing_buffer to make

And improve documentation.