Optimise point.h

[VyasGuru]

Optimize point class arithmetic

Summary

This PR introduces significant performance optimizations to the core point class.

Changes

Performance Optimizations

• File: include/cartesian_geom/point.h
• 1-> (squared_length):
  • Replaced return length() * length() with return coeffs.squaredNorm().
  • Benefit: Eliminates an expensive square root instruction followed by a multiplication. This improves performance for distance-based checks and increases precision by avoiding floating-point errors.
• 2->(Overloading):
  • Added template overloads for operator+= and operator-= that accept Eigen::MatrixBase<Derived>.
  • Benefit: Enables lazy evaluation, improving performance by reducing memory load.

Adresses #434
@vissarion please do look into this if there are any further changes to be made.