* umm_malloc manual merge with upstream
* Fix divide by zero, case when heap is 100% allocated.
* Removed extra line.
* Fixed block count for debug build. This resolves OOM events for debug build.
Correct overstepping array when freeing.
* Handle another corner case in example HeapMetric.ino.
Comment corrections.
* Revert - ESP.getMaxFreeBlockSize() is back to indicating the size of a
contiguous block of memory before the umm_malloc overhead is removed.
* Stale code cleanup and comment improvements
83523c0259