Enforce enlargeCore to take only 1 newObject at a time rather than a list.
Enforce enlargeCore to take only 1 newObject at a time rather than a list.

We are already doing this in our algorithm by adding a single species at a time.
Simplify the internal code to ensure it only accepts 1 new species at a time.

nyee/RMG-Py,chatelak/RMG-Py,nickvandewiele/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,nickvandewiele/RMG-Py