
TODO:

 * some way of specifying environment for subprocesses
 * concat should use two passes, one to calculate the string's length
   the second to build it.
 * areas as input streams?
 * find-*-* can be told where to stop?
 * notification when a file changes externally
 * find-*-string can be case-insignificant
 * buffer lines should be allocated in multiples of 8 characters
 * trap SIGTERM/SIGHUP?
