Implement multithreaded algorithms

Create implementations for parallel and multithreaded algorithm patterns in Hy:

## Parallelization patterns:
- Map-reduce
- Fork-join
- Pipeline processing
- Worker pool
- Producer-consumer
- Master-worker

## Parallel algorithms:
- Parallel merge sort
- Parallel quick sort
- Parallel matrix multiplication
- Parallel prefix sum (scan)
- Parallel breadth-first search
- Parallel graph algorithms

## Synchronization primitives:
- Locks and mutexes
- Semaphores
- Barriers
- Condition variables
- Atomic operations

## Requirements:
- Provide detailed complexity and speedup analysis
- Include scalability considerations
- Create comprehensive test cases with benchmarks
- Document parallel algorithm design patterns

This collection will demonstrate effective techniques for leveraging multi-core processors and parallel computing architectures using Hy's capabilities for interacting with Python's parallel processing libraries.