Fixes makefile to build without 'array.h'
Changes idle logic... See below

    Now, when ashuffle starts, it will enqueue a new song and start
    playing if mpd is not currently playing. This is to avoid the
    situation where I was playing music yesterday, I pause the music,
    come back the next day and want to shuffle.

    Also, I simplified the enqueue logic so that it doesn't require any
    persistent variables and still behaves properly. This also fixes the
    bug where stopping play in the middle of the queue automatically
    adds another song to the queue and continue playing.