Method observe

src/com/winvector/util/CountMap.java:28–35

Invariant: key set calls all keys ever observed (even those with net-zero count) @param key @param delta

(final T key, final double delta)

	 * @param delta
	 */
	public void observe(final T key, final double delta) {
		MutableDouble v = counts.get(key);
		if(v==null) {
			v = new MutableDouble();
			counts.put(key,v);
		}
		v.v += delta;
	}
	
	public void observe(final CountMap<T> o) {
		for(final T k: o.keySet()) {