v2.1.6

• [New] Add German support (chrono.de)
• [New] Improve vague timeunit expressions parsing (e.g. in around 2 hours)
• [New] Better casual unit parsing support (e.g. -4hr3min, or next 3weeek 4days)
• [Fix] Use null instead of undefined in timezone (see #340)

v2.1.5...v2.1.6