Add capacity limit for engagement creation for an opportunity

[flxcn]

Two versions of a similar feature;

1. Add a field to opportunities specifying the limit for the number of times an engagement can be created for a specific opportunity. The default would be 1, perhaps it could be implemented by a radio button

2. For the total number of positions, enforce a check on the number to ensure it is not surpassed. Or include a "do not enforce" option for the limit (perhaps a check box?)