logrw: The log reads/writes package.

This directory implements a library for reading and writing from/to a 
buffer using a log structure. It supports using
a native (OS-provided) pthreads implementation as well as user-level
thread package (the later to be implemented by the student).

The public API is described in ../include/logrw.h. 
logrw.c (to be implemented by the student) implements this API.
block.c implements a storage layer which offers the abstraction 
of a sequence of blocks of fixed size. Blocks are kept in memory.
Contains functions for creating, destroying, writing, reading and 
dumping blocks, among other. 
io_delay.c implements a delay (can be used for reading or writing 
delays) by puting a thread to sleep for a specified duration.
