Coin Identifying

Added:
- find_coins() - finds the coins by taking perpendicular bisectors to a
number of chords on each suspected coin, disregarding duplicates and
coins with diameter below a certain threshold.

Moved to old_code.cpp:
- find_borders() - no longer necesisary

To Do:
- modularize diameter function so more accurate diameters can be
calculated
- use modular diameter function to increase accuracy of center point