More performance tweaks for Sage interface
More performance tweaks for Sage interface

- _coerce_impl now works with syntax only,
- eleminate some calls to bool,
- don't do iterations if there are not needed,
- construct concept lattice with strings and not with ExpectElements.

Signed-off-by: Daniel Borchmann <25857343a15bf1edafebc2912e82ecf775c585c1@mailbox.tu-dresden.de>

fcatools/conexp-clj,Lobage/conexp-clj,fcatools/conexp-clj,Lobage/conexp-clj,exot/conexp-clj,exot/conexp-clj,fcatools/conexp-clj,Lobage/conexp-clj,fcatools/conexp-clj,fcatools/conexp-clj,exot/conexp-clj,exot/conexp-clj,exot/conexp-clj,Lobage/conexp-clj