Crude user-interactivity deployed

Crude framework. Can currently only start and top playback of file ATM. This
commit is a proof of concept. Most if not all is contained in new file(s)
outside of current HEMUL scope.

Future features could be:

* Entering command mode (-o and -i flag deployed)
* Changing interactive flow via -O and -I flags (stdin/stdout files). By
  rerouting these to prepared named pipes, control over tcp can be deployed
  with ease.
* With or without stopping replay first
* Shortcuts (keys) for operation without feedback
   1) Toggling or
   2) setting arguments that affect flow
   I.e. period-time, buffering
* Functions of interest.
   1) Flush on demand
   2) Playing backwards
   3) Changing buffer-size
   4) Composing specific buffer out of lines

Need curses for this? Hopefully not, or transparency over tcp will likely
not work.

References: man struct termios
Pause also flushing.

It does not make sense to allow flushing when output is supposed to be
paused. It will only trigger iNotify for no reason. Also changing from
semaphores to mutexes as they are easier to deploy in this scenario.