Add list.c to dependencies.
Commented the printf in the end of count_characters because it is only a test function.
Nothing changed, only a empty line at the end of the file.
Implemented node's creation function. Also implemented a queue's initialization, insertion, remotion and printing functions. Implemented a array of leaves, containing the same characters of the queue and its creation function. Implemented a function to get the number of nodes of p_queue.
Now it has the prototype of all new function of list.c.
Now they are empty. We will implement them in a near future.