Fix up/downtrend thresholds MACD (#223)

* Fix up/downtrend thresholds

The thresholds were only reacting on the first period of the MACD trend. After this they did not respond as the last period was already positive or negative.

With this it will take the threshold in consideration as well.

* Uniform/Clear conditions

conditionis in the form of: if (a - t > 0 && b - t <= 0) / if (a + t < 0 && b + t >= 0)

extensions/macd/strategy.js

@@ -52,9 +52,9 @@ module.exports = function container (get, set, clear) {
       }
 
       if (typeof s.period.macd_histogram === 'number' && typeof s.lookback[0].macd_histogram === 'number') {
-        if (s.period.macd_histogram > s.options.up_trend_threshold && s.lookback[0].macd_histogram <= 0) {
+        if ((s.period.macd_histogram - s.options.up_trend_threshold) > 0 && (s.lookback[0].macd_histogram - s.options.up_trend_threshold) <= 0) {
           s.signal = 'buy';
-        } else if (s.period.macd_histogram < -s.options.down_trend_threshold && s.lookback[0].macd_histogram >= 0) {
+        } else if ((s.period.macd_histogram + s.options.down_trend_threshold) < 0 && (s.lookback[0].macd_histogram + s.options.down_trend_threshold) >= 0) {
           s.signal = 'sell';
         } else {
           s.signal = null;  // hold