Fix cell soup in center of late development epithelium

[lavinrp]

This is from a 10000 cell epithelium generated with default settings and run with default settings.
Everything seems fine until cells start to die.

[lavinrp]

This seems to be caused by cells continuing to grow after specialization. This causes LOTS of collision issues in the center of the epithelium where its not easy for cells to find a empty space. Eventually the Support cells start to wedge themselves into the ommatidium.

@shubhamTR
There are a LOT of variables at play to produce this.

1. Cell Adhesion values may not be optimal.
   • If R* cells had stronger adhesion to each other than to support cells that may help the issue
2. Cell growth rate may not be optimal
   • The cells are growing quickly causing them to push into each other. A slower (or zero) growth rate of specialized cells may alleviate this.
     • Specialized is bold b/c the growth of the unspecialized cells doesn't really impact this much right now
3. Cells may be allowed to grow too big
   • By default tehse cells won't divide until they are 2.5 times the size they start at. This causes a lot of pushing.
4. Internal cell collision logic may not be good enough.