reteclock 0.12.0

* The timer's finishing tune is the theme from the fourth movement of Schubert's Trout Quintet - the washing-machine tune - played from the score rather than recorded. The beeps lost the buzz of a square wave. * An interval's two colours now mean what they say: the first is the bar before the fill has passed it, the second is the bar after. Either can be left empty, and the clock shows through. * Colours can be typed as #RRGGBB as well as picked. * The timer works to the second: no more