Build an XML mission string.

def getMissionXML(summary):
    ''' Build an XML mission string.'''
    spawn_end_tag = ' type="mob_spawner" variant="' + MOB_TYPE + '"/>'
    return '''<?xml version="1.0" encoding="UTF-8" ?>
    <Mission xmlns="http://ProjectMalmo.microsoft.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
        <About>
            <Summary>''' + summary + '''</Summary>
        </About>

        <ModSettings>
            <MsPerTick>20</MsPerTick>
        </ModSettings>
        <ServerSection>
            <ServerInitialConditions>
                <Time>
                    <StartTime>13000</StartTime>
                    <AllowPassageOfTime>false</AllowPassageOfTime>
                </Time>
                <AllowSpawning>true</AllowSpawning>
                <AllowedMobs>''' + MOB_TYPE + '''</AllowedMobs>
            </ServerInitialConditions>
            <ServerHandlers>
                <FlatWorldGenerator generatorString="3;7,220*1,5*3,2;3;,biome_1" />
                <DrawingDecorator>
                    <DrawCuboid ''' + getCorner("1",True,True,expand=1) + " " + getCorner("2",False,False,y=226,expand=1) + ''' type="stone"/>
                    <DrawCuboid ''' + getCorner("1",True,True,y=207) + " " + getCorner("2",False,False,y=226) + ''' type="air"/>

                    <DrawLine ''' + getCorner("1",True,True) + " " + getCorner("2",True,False) + spawn_end_tag + '''
                    <DrawLine ''' + getCorner("1",True,True) + " " + getCorner("2",False,True) + spawn_end_tag + '''
                    <DrawLine ''' + getCorner("1",False,False) + " " + getCorner("2",True,False) + spawn_end_tag + '''
                    <DrawLine ''' + getCorner("1",False,False) + " " + getCorner("2",False,True) + spawn_end_tag + '''
                    <DrawCuboid x1="-1" y1="206" z1="-1" x2="1" y2="206" z2="1" ''' + spawn_end_tag + '''
                    ''' + getItemXML() + '''
                </DrawingDecorator>
                <ServerQuitWhenAnyAgentFinishes />
            </ServerHandlers>
        </ServerSection>

        <AgentSection mode="Survival">
            <Name>The Hunted</Name>
            <AgentStart>
                <Placement x="0.5" y="207.0" z="0.5"/>
                <Inventory>
                </Inventory>
            </AgentStart>
            <AgentHandlers>
                <ChatCommands/>
                <ContinuousMovementCommands turnSpeedDegs="360"/>
                <AbsoluteMovementCommands/>
                <ObservationFromNearbyEntities>
                    <Range name="entities" xrange="'''+str(ARENA_WIDTH)+'''" yrange="2" zrange="'''+str(ARENA_BREADTH)+'''" />
                </ObservationFromNearbyEntities>
                <ObservationFromFullStats/>
                <RewardForCollectingItem>
                    <Item type="'''+GOAL_TYPE+'''" reward="'''+str(GOAL_REWARD)+'''"/>
                </RewardForCollectingItem>''' + malmoutils.get_video_xml(agent_host) + '''
            </AgentHandlers>
        </AgentSection>

    </Mission>'''