made popping with lists work. yay! (also new demo to show the thing)

include/list.h

@@ -17,10 +17,12 @@ typedef struct {
     vector_t* data;         // vector of vectors
 } list_t;
 
-list_t* listInit();                         // returns a new list
+list_t* listInit();                                             // returns a new list
 
-void listPush(list_t* l, dataType_e type, void* element);    // appends an element at the end of a list
+void listPush(list_t* l, dataType_e type, void* element);       // appends an element at the end of a list
 
-void listPrint(list_t* l);                  // prints a list
+void listPrint(list_t* l);                                      // prints a list
 
-void listCleanup(list_t* l);                         // freeing pointers
+void listCleanup(list_t* l);                                    // freeing pointers
+
+void* listPop(list_t* l);                                       // popping the last value of the list and returning it