Valetudo 0.3.1-RE4 preview

Fourth release for testing RE version, verified on S55 (fw 1864).

New features added:

• Viewing maps of history cleaning runs (works most of the time);
• Compression for map transferring via websocket connection (saves bandwidth up to 5x);
• Support of Daylight Saving Time in scheduled zoned cleaning.

Node.js updated to 10.15.3.

Also includes all upstream updates till 14 jul 2019.