Allow all possible values for maxNearestNeighb. from learning

in tracking with learning maxNearestNeighbours can have values up to 9 and
users expect to be able to transfer values from tracking with learning to
conservation tracking.

ilastik/applets/tracking/conservation/drawer.ui

@@ -380,7 +380,7 @@
           <number>1</number>
          </property>
          <property name="maximum">
-          <number>5</number>
+          <number>9</number>
          </property>
          <property name="value">
           <number>3</number>