Support for user icons when importing KMZ

[Korb]

Currently, thanks to @cdauth in facilmap.org there is the possibility of importing kmz-files (#47). However, if you use a file generated in the Google My Maps for imports, groups and icons (icons) are lost during imports. Because of this, large sets of labels previously structured using three independent parameters (group, icon and color) after import are turned into a uniform set of labels that are difficult to use: