added methods: getMap, getData;
added options: intensityOfMidpoint (instead of medianOfGradient),
radius (instead of pointRadius);
all static utils: removed from objects

remove _layer filed from TileUrlGenerator; added dependence for points size from zoom; added medianaOfGradient parameter

optimize destroy methods; create method setData for heatmap instead of addPoints and removePoints; added weight parameter for points

tiny speed optimization: added tile cache layer; exec _isPointInBounds function without request to option manager