create-unit: add nickname option

scripts/modtools/create-unit.lua

@@ -330,6 +330,7 @@ validArgs = --[[validArgs or]]utils.invert({
   'flagSet',
   'flagClear',
   'name',
+  'nick',
   'location',
   'age'
 })
@@ -369,6 +370,8 @@ arguments:
         set the unit's name to be a random name appropriate for the given entity
         examples:
             MOUNTAIN
+    -nick nickname
+        set the unit's nickname directly
     -location [ x y z ]
         create the unit at the specified coordinates
     -age howOld
@@ -505,6 +508,10 @@ else
   end--]]
 end
 
+if args.nick and type(args.nick) == 'string' then
+  dfhack.units.setNickname(df.unit.find(unitId), args.nick)
+end
+
 if civ_id then
   local u = df.unit.find(unitId)
   u.civ_id = civ_id