Variable is a size so use size_t rather than an int.
Change variable type and add comments to algorithm.
Initialise isomer energy value and make sure lowest partition is positive.

There is no need to set the gs isomeric data to an 'obvious' value, lets
initialise it to <0 even though we can filter out gs by checking value
of the st member.

As a follow up to new initialisation, we need to ensure that only
positive values are displayed in the colour of the first element of
partition object.
Use the fact that find_first_of() can search for multiple characters.
Add comments to explain the extraction of the decay mode.

Also change vector type from int->bool as we are only using it
for a yes/no check.
Use a bool instead of int as value is on;y 0/1.
Lessen scope of a variable and alter member rather than modifying local before assigning.