Root system improved and updated with work with tendrils.

[Tientuine]

Includes the following changes:

• Improvements to the basic rooting mechanic
  • Seed should no longer pass through other Rigidbody when rooted
  • Attachment points are defined more simply and appropriately
  • Adjusted positioning of the root collider and tendrils for improved function and form
• Enhancement of the roots and root system
  • Now uses tendrils for the visual presentation of roots when grown out
  • Added a root stub (the "radicle") for improved appearance when roots are not grown
  • Uprooting now breaks off the root tendrils and leaves them behind
• Code cleanup
  • Removed all magic numbers
  • Useful parameters are now exposed in the Inspector
  • Refactored a number of methods and symbols
  • Added documentation comments