- Changed mem_malloc(): near fit behaves like exact fit since mem->next is always used

- Included some more alignment statements
- Every malloced block is at least MIN_SIZE big (can be overridden, can be used to work against fragmentation)
- Added many comments so that the next developer knows what I was thinking :-)

src/include/lwip/mem.h

@@ -39,6 +39,9 @@
 extern "C" {
 #endif
 
+/* MEM_SIZE would have to be aligned, but using 64000 here instead of
+ * 65535 leaves some room for alignment...
+ */
 #if MEM_SIZE > 64000l
 typedef u32_t mem_size_t;
 #define MEM_SIZE_F U32_F