Summary
- clarified File_Format.detect: needs to operate on full node name;
- more accurate syntax, following Sessions.parse_roots in Scala;
- PIDE support for session ROOTS;
- more robust;
- more Unicode;
- eliminated odd "Read_me";
- eliminated odd "Read_me";
- tuned signature;
- silently ignore markup that starts out as singularity, e.g. <language/> from empty ML file;
- moved some lemmas from AFP to distribution