A simple C++ wrapper for Unix file I/O.

This is intended to be lightweight and easy to use, similar to Java's RandomAccessFile and related classes. The usual C++ idioms of RAII and "you don't pay for what you don't use" apply.

In particular, the basic RandomAccessFile interface is kept small and simple so it's trivial to add new implementations.

This code will not log, because it can't know whether that's appropriate in your application.

This code will, in general, return -errno on failure. If an operation consisted of multiple sub-operations, it will return the errno corresponding to the most relevant operation.