Upgrade the implementation of dynamic memory allocator:

[AwenChen]

1. Allocate memory with alignment in case of the crash in some embedded system;
2. Free memory without coalesce the next node(or previous node) when the current node is the last one(or first one);
3. Add declaration of function get_best_fit in case of crash in 64bits platform;
4. Fix the dump of pointer in main.c;