Add tests for farith2

colibri2.opam

colibrics.opam

dune

farith2/extract/farith_Big.ml

farith2/farith2.ml

farith2/farith2.mli

farith2/tests/issue_005.expected

farith2/tests/issue_005.ml

farith2/tests/mode.expected

farith2/tests/mode.ml

farith2/tests/subnormal.expected

farith2/tests/subnormal.ml

farith2/tests/test.expected

farith2/tests/test.ml

farith2/tests/tie.expected

farith2/tests/tie.ml

src_colibri2/theories/FP/fp_value.ml