Value processing and fallbacks

[ivankokan]

CesiumHeatmap/CesiumHeatmap.js

Line 305 in 898d286

if (gp.value || gp.value === 0) {

CesiumHeatmap/CesiumHeatmap.js

Line 419 in 898d286

var j = a[this._valueField] || 1;

CesiumHeatmap/CesiumHeatmap.js

Line 476 in 898d286

this._min = a.min || 0;

I consider these lines very context-specific and not valid in general.
L305: Original value should be used, even if it is undefined or null.
L419: All 0 values will be considered as 1? Using non-processed original will do in general case.
L476: Not sure what to do here, remove || 0 from min-part or make something similar within max-part.

All those repeat in HeatmapImageryProvider.js.