world: ignore poi directory in world dir

This is a new directory added in 1.14 which contains .mca files too.

Since we scan for directories with .mca files to use as RegionSets,
and we don't know how to handle these, just skip them.

Fixes some warnings during rendering.

overviewer_core/world.py

@@ -134,6 +134,7 @@ class World(object):
             if mcas:
                 # construct a regionset object for this
                 rel = os.path.relpath(root, self.worlddir)
+                if rel != "poi":
                     rset = RegionSet(root, rel)
                     if root == os.path.join(self.worlddir, "region"):
                         self.regionsets.insert(0, rset)
@@ -272,7 +273,7 @@ class RegionSet(object):
             # this is the main world
             self.type = None
         else:
-            logging.warning("Unkown region type in %r", regiondir)
+            logging.warning("Unknown region type in %r", regiondir)
             self.type = "__unknown"
 
         logging.debug("Scanning regions.  Type is %r" % self.type)