[units]Add millimeter support (input only)

units.py

@@ -11,7 +11,7 @@
 import re
 
 find_temp = re.compile('(-?[0-9]*\.?[0-9]*)[ °]*(K|C|F)', re.IGNORECASE)
-find_length = re.compile('([0-9]*\.?[0-9]*)[ ]*(mile[s]?|mi|inch|in|foot|feet|ft|yard[s]?|yd|(?:centi|kilo|)meter[s]?|[kc]?m)', re.IGNORECASE)
+find_length = re.compile('([0-9]*\.?[0-9]*)[ ]*(mile[s]?|mi|inch|in|foot|feet|ft|yard[s]?|yd|(?:milli|centi|kilo|)meter[s]?|[mkc]?m)', re.IGNORECASE)
 find_mass = re.compile('([0-9]*\.?[0-9]*)[ ]*(lb|lbm|pound[s]?|ounce|oz|(?:kilo|)gram(?:me|)[s]?|[k]?g)', re.IGNORECASE)
 
 
@@ -81,6 +81,8 @@ def distance(bot, trigger):
     meter = 0
     if unit in ("meters", "meter", "m"):
         meter = numeric
+    elif unit in ("millimeters", "millimeter", "mm"):
+        meter = numeric / 1000
     elif unit in ("kilometers", "kilometer", "km"):
         meter = numeric * 1000
     elif unit in ("miles", "mile", "mi"):
@@ -96,6 +98,7 @@ def distance(bot, trigger):
 
     if meter >= 1000:
         metric_part = '{:.2f}km'.format(meter / 1000)
+    #TODO, Maybe: elif meter < 0.01, display in millimeters?
     elif meter < 1:
         metric_part = '{:.2f}cm'.format(meter * 100)
     else: