Started Mutexing

Started process of mutexing critical code (linked list operations)
Added Mutexing

Mutexes have been implemented, and a function for removing old nodes has
been created. However, it is throwing run-time errors when attempting to
delete as SocketNode.
Fixed node deletion bug

runtime error would occur when deleting a clientnode, this occurred
because the delete command would also terminate the clientnode's thread,
which was the currently running thread. Detaching the thread from its
handle fixed the error.