Submitting rmem memory and object pool module (#898)

* Submitting rmem memory and object pool module

* changed 'restrict' to '__restrict' so it can compile for MSVC

Added `const` to parameters for `MemPool_Realloc`

* Update and rename mempool README.txt to mempool_README.md

* Update mempool_README.md

* Update mempool_README.md

* Update and rename objpool README.txt to objpool_README.md

* implementing changes

* updating header for changes.

* forgot to change _RemoveNode to __RemoveNode

* removing l

* removing l

* Updating documentation on MemPool_CleanUp function

* Updating documentation on ObjPool_CleanUp function

* changed *_CleanUp function parameter

Replaced `void*` pointer to pointer param to `void**` so it's more explicit.

* Updating header to reflect changes to the *_CleanUp functions

* A single change for the mempool and a patch for the objpool.

Object Pool Patch: if you deplete the object pool to 0 free blocks and then free back one block, the last given block will be rejected because it was exactly at the memory holding the entire pool.
Mempool change: switched memory aligning the size from the constructor to when allocating.

src/rmem.h

@@ -0,0 +1,75 @@
+#ifndef RAYLIB_MEMORY_INCLUDED
+#    define RAYLIB_MEMORY_INCLUDED
+
+
+#include <stdlib.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <string.h>
+
+/************* Memory Pool (mempool.c) *************/
+typedef struct MemNode {
+    size_t size;
+    struct MemNode *next, *prev;
+} MemNode;
+
+typedef struct AllocList {
+    struct MemNode *head, *tail;
+    size_t len, maxNodes;
+    bool autoDefrag : 1;
+} AllocList;
+
+typedef struct Stack {
+    uint8_t *mem, *base;
+    size_t size;
+} Stack;
+
+typedef struct MemPool {
+    struct AllocList freeList;
+    struct Stack stack;
+} MemPool;
+/***************************************************/
+
+
+/************* Object Pool *************/
+typedef struct ObjPool {
+    struct Stack stack;
+    size_t objSize, freeBlocks;
+} ObjPool;
+/***************************************************/
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/************* Memory Pool *************/
+struct MemPool MemPool_Create(size_t bytes);
+struct MemPool MemPool_FromBuffer(void *buf, size_t bytes);
+void MemPool_Destroy(struct MemPool *mempool);
+
+void *MemPool_Alloc(struct MemPool *mempool, size_t bytes);
+void *MemPool_Realloc(struct MemPool *mempool, void *ptr, size_t bytes);
+void MemPool_Free(struct MemPool *mempool, void *ptr);
+void MemPool_CleanUp(struct MemPool *mempool, void **ptrref);
+
+size_t MemPool_MemoryRemaining(const struct MemPool mempool);
+bool MemPool_DeFrag(struct MemPool *mempool);
+void MemPool_ToggleAutoDefrag(struct MemPool *mempool);
+/***************************************************/
+
+/************* Object Pool (objpool.c) *************/
+struct ObjPool ObjPool_Create(size_t objsize, size_t len);
+struct ObjPool ObjPool_FromBuffer(void *buf, size_t objsize, size_t len);
+void ObjPool_Destroy(struct ObjPool *objpool);
+
+void *ObjPool_Alloc(struct ObjPool *objpool);
+void ObjPool_Free(struct ObjPool *objpool, void *ptr);
+void ObjPool_CleanUp(struct ObjPool *objpool, void **ptrref);
+/***************************************************/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* RAYLIB_MEMORY_INCLUDED */