Simple MATLAB function for plot multi-channel time-series data

Usage:
   plot_multichan( y ) % <- y: signal
   plot_multichan( x, y ) % <- x: time

Example:
   y = randn([10, 200]);
   plot_multichan(y);

Written by Hio-Been han, hiobeen.han@kaist.ac.kr
Initial commit @2020-03-07