function inflate(folds) {
        if (!folds) {
            return;
        }
         //transform the folds into objects with from and to properties
        var ranges = {}, obj;
        Object.keys(folds).forEach(function (line) {
            obj = folds[line];
            ranges[line] = {from: {line: obj[0][0], ch: obj[0][1]}, to: {line: obj[1][0], ch: obj[1][1]}};
        });

        return ranges;
    }
Inflates the fold ranges stored as simplified numeric arrays. The inflation converts the data into
objects whose keys are line numbers and whose values are objects in the format {from: {line, ch}, to: {line, ch}}.
@param {Object}  folds the simplified fold ranges
@return {Object} the converted fold ranges