Fix(Core): refact MO, clean import and fix renders

Split MO in 2 categories Atoms and Molecules

mapytex/calculus/core/compute/minus.py

@@ -12,7 +12,7 @@ Minus MO: take the opposit
 
 from multipledispatch import Dispatcher
 from .exceptions import MinusError
-from ..MO.mo import MO, MOnumber, MOstr
+from ..MO import MO, MOnumber, MOstr
 from ..MO.fraction import MOFraction
 from ..MO.monomial import MOstrPower, MOMonomial
 from ..MO.polynomial import MOpolynomial