Add draw pullup penalty preference.

tabbycat/options/preferences.py

@@ -288,6 +288,23 @@ class DrawPullupRestriction(ChoicePreference):
     default = 'none'
 
 
+@tournament_preferences_registry.register
+class DrawPullupPenalty(IntegerPreference):
+    help_text = _("If using pull-ups, prefer which teams can be pulled up. "
+        "Two-team formats only. Has no effect on BP or intermediate brackets."
+        "Note: this applies a penalty (making solutions which do not satisfy this preference less\
+            likely to appear). If you want to entirely reject such draws, you should use the\
+            pullup restriction preference instead.")
+    verbose_name = _("Pullup penalty")
+    section = draw_rules
+    name = 'draw_pullup_penalty'
+    choices = (
+        ('none', _("No penalty")),
+        ('lowest_ds_rank', _("Prefer teams with a lower draw strength by rank")),
+    )
+    default = 'none'
+
+
 @tournament_preferences_registry.register
 class BPPullupDistribution(ChoicePreference):
     help_text = _("In BP, how pullups are distributed. Only \"Anywhere\" is WUDC-compliant.")