ExcludeReactants

[kaizu]

The following doesn't work now:

https://github.com/ecell/ecell4/blob/master/python/samples/reaction_reader/Haugh2b/Haugh2b.py#L17

This means that the second reactant must have not R in it. This is originally in BNGL, but the representation looks unfamiliar for me. Propose new expression to do the same thing.

[kaizu]

The original:

A(x) + B(x) > A(x^1).B(x^1) | k | ExcludeReactants(2, A)
A(x) + B(x) > A(x^1).B(x^1) | k | exclude_reactants(2, A)

Proposals:

A(x) + B(x)._withno(A) > A(x^1).B(x^1) | k
A(x) + B(x)^A > A(x^1).B(x^1) | k
A(x) + _exclude(B(x), A) > A(x^1).B(x^1) | k

The above is okay for left-to-right, but now good for right-to-left representation.