Added extrapolated "name_exists" function.

Note that this can move, I just put it where it made
the most sense.

Code that checks for account names and aliases can
now be replaced with (assuming this is imported):

functions_user.name_exists("username")

If there is an alias match or an account match, it
will return True.

src/util/functions_user.py

@@ -0,0 +1,30 @@
+"""
+User-related functions
+"""
+from django.contrib.auth.models import User
+
+from src.object.models import Attribute, Object
+from src import defines_global
+
+def name_exists(uname):
+    """
+    Searches for an account first by username, then by alias.
+
+    uname: (string) A username or alias
+    
+    returns True or False
+    """
+
+    # Search for a user object with username = uname
+    account = User.objects.filter(username=uname)
+    # Look for any objects with an 'Alias' attribute that matches
+    # the uname
+    alias_matches = Object.objects.filter(attribute__attr_name__exact="ALIAS",
+        attribute__attr_value__iexact=uname).filter(
+            type=defines_global.OTYPE_PLAYER)
+    
+    if not account.count() == 0 or not alias_matches.count() == 0:
+        return True
+
+    return False
+