Added linkedlist node functions

examples/linked_list_node.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <assert.h>
+#include "../src/linkedlist.h"
+
+LINKEDLIST_GENERATE(l, list, , , int)
+
+int main(int argc, char const *argv[])
+{
+    list *l = l_new();
+
+    for (int i = 0; i < 97; i++)
+        l_push_back(l, i);
+
+    // Add 99 after and 33 before every node where its data is divisible by 3
+    for (list_node *node = l->head; node != NULL; node = node->next)
+    {
+        if (node->data % 3 == 0)
+        {
+            l_insert_prv(node, 33);
+            l_insert_nxt(node, 99);
+            node = node->next; // skip 99
+        }
+    }
+
+    size_t s = 0;
+    for (list_node *node = l->head; node != NULL; node = node->next, s++)
+    {
+        if (node->prev == NULL)
+            printf("[ %d, ", node->data);
+        else if (node->next == NULL)
+            printf("%d ]\n", node->data);
+        else
+            printf("%d, ", node->data);
+    }
+
+    printf("List Head: %d\nList Tail: %d\nList Count: %d\n", l->head->data, l->tail->data, l->count);
+
+    assert(s == l->count);
+
+    l_free(l);
+
+    return 0;
+}