Binary heaps

A binary heap is an extremely efficient structure for specific uses. PicoTCP uses a heap to store timers. The whole implementation is in heap.h and consists of a single preprocessor macro spread across 75 lines of code. This implementation of the binary heap is type-agnostic, but in picoTCP is only used to store timers so far. Please refer to the section Timers for the usage of the timer interface.