- Updated n_chase to support bidirectional movement with n3 and n4 parameters
- n3 controls forward steps per direction change
- n4 controls backward steps per direction change
- Pattern alternates between moving forward n3 steps and backward n4 steps
- Each direction repeats for the specified number of steps before switching
- Added test/9.py with n1=20, n2=20, n3=20, n4=-5 parameters
- Updated to run as a thread-based pattern similar to other patterns
