Implement memory.grow and limit heap space base offset to 1G (#36)

* Implement memory profiler, optimize memory usage, modify code indent

* Implement memory.grow and limit heap space base offset to 1G; modify iwasm build type to Release and 64 bit by default

core/shared-lib/include/bh_memory.h

@@ -52,6 +52,12 @@ int bh_memory_init_with_allocator(void *malloc_func, void *free_func);
  */
 void bh_memory_destroy();
 
+/**
+ * Get the pool size of memory, if memory is initialized with allocator,
+ * return 1GB by default.
+ */
+int bh_memory_pool_size();
+
 #if BEIHAI_ENABLE_MEMORY_PROFILING == 0
 
 /**