cuos: Interface to the Operating System

Modules
	cuos/file.h: Functions on Files
	cuos/fs.h: File System
	cuos/fwd.h: Forward Declarations
	cuos/dirpile.h: Prioritised Collection of Search Directories
	cuos/dsink.h: Binding Data Sinks to Resources
	cuos/path.h: File path functions
	cuos/process.h: Running external processes
	cuos/time.h: System and process time and related.
	cuos/user_dirs.h: User Directories as Defined by XDG