[ground_segment] add joystick hat to input2ivy

You can use the Hat<Position>(<hat_name>) function to trigger events,
where <Position> is one of
Centered/Up/Right/Down/Left/RightUp/RightDown/LeftUp/LeftDown

Only one hat can be used, but the interface will allow multiple ones in
the future.

closes #460

conf/joystick/ms_sidewinder.xml

@@ -4,8 +4,6 @@
   axis 1: pitch
   axis 2: yaw
   axis 3: throttle (reversed)
-  axis 4: hat switch left/right (right is positive)
-  axis 5: hat switch up/down (down is positive)
 
 It has 9 buttons.
  b0  - fire
@@ -18,6 +16,11 @@ It has 9 buttons.
  b7  - button D
  b8  - shift button
 
+and a POV hat.
+You can use the Hat<Position>(<hat_name>) function to trigger events,
+where <Position> is one of
+Centered/Up/Right/Down/Left/RightUp/RightDown/LeftUp/LeftDown
+so e.g. HatDown(myhat)
 -->
 
 <joystick>
@@ -26,8 +29,6 @@ It has 9 buttons.
     <axis index="1" name="pitch" limit="1.00" exponent="0.7" trim="0"/>
     <axis index="2" name="yaw" limit="1.00" exponent="0.7" trim="0"/>
     <axis index="3" name="throttle"/>
-    <axis index="4" name="hat_lr"/>
-    <axis index="5" name="hat_ud"/>
     <button index="0" name="fire"/>
     <button index="1" name="fire2"/>
     <button index="2" name="up"/>
@@ -37,23 +38,28 @@ It has 9 buttons.
     <button index="6" name="C"/>
     <button index="7" name="D"/>
     <button index="8" name="shift"/>
+    <hat index="0" name="hat"/>
   </input>
 
   <messages period="0.1">
 
-    <!--message class="datalink" name="RC_4CH" send_always="true">
+    <message class="datalink" name="RC_4CH" send_always="true">
       <field name="mode" value="1-fire+A"/>
       <field name="throttle" value="Fit(-throttle,-127,127,0,127)"/>
       <field name="roll" value="roll"/>
       <field name="pitch" value="pitch"/>
       <field name="yaw" value="yaw"/>
-    </message-->
+    </message>
 
-    <message class="datalink" name="RC_3CH" send_always="true">
+    <message class="ground" name="JUMP_TO_BLOCK" on_event="HatDown(hat)">
+      <field name="block_id" value="IndexOfBlock('land')"/>
+    </message>
+
+    <!--message class="datalink" name="RC_3CH" send_always="true">
       <field name="throttle_mode" value="0"/>
       <field name="roll" value="roll"/>
       <field name="pitch" value="pitch"/>
-    </message>
+    </message-->
 
   </messages>
 </joystick>

conf/joystick/xbox_gamepad.xml

@@ -0,0 +1,67 @@
+<!-- Generic X-Box gamepad, e.g. Logitech wireless gamepad F710
+  Has six axes:
+  axis 0: LTS_H (left thumb stick horizontal) (or DPad horizontal in alternate mode)
+  axis 1: LTS_V (left thumb stick vertical) (or DPad vertical in alternate mode)
+  axis 2: LT (left trigger)
+  axis 3: RTS_H (right thumb stick horizontal)
+  axis 4: RTS_V (right thumb stick vertical)
+  axis 5: RT (right trigger)
+
+It has 11 buttons.
+ b0  - A
+ b1  - B
+ b2  - X
+ b3  - Y
+ b4  - LB (left button)
+ b5  - RB (right button)
+ b6  - back
+ b7  - start
+ b8  - ?
+ b9  - LSB (left stick button)
+ b10 - RSB (right stick button)
+
+and the DPad as a hat (in normal mode)
+You can use the Hat<Position>(<hat_name>) function to trigger events,
+where <Position> is one of
+Centered/Up/Right/Down/Left/RightUp/RightDown/LeftUp/LeftDown
+so e.g. HatDown(dpad)
+-->
+
+<joystick>
+  <input>
+    <axis index="0" name="yaw" limit="1.00" exponent="0.7" trim="0"/>
+    <axis index="1" name="throttle"/>
+    <axis index="2" name="LT" limit="1.00" trim="127"/>
+    <axis index="3" name="roll" limit="1.00" exponent="0.7" trim="0"/>
+    <axis index="4" name="pitch" limit="1.00" exponent="0.7" trim="0"/>
+    <axis index="5" name="RT" limit="1.00" trim="127"/>
+    <button index="0" name="A"/>
+    <button index="1" name="B"/>
+    <button index="2" name="X"/>
+    <button index="3" name="Y"/>
+    <button index="4" name="LB"/>
+    <button index="5" name="RB"/>
+    <button index="6" name="back"/>
+    <button index="7" name="start"/>
+    <button index="9" name="LSB"/>
+    <button index="10" name="RSB"/>
+    <hat index="0" name="dpad"/>
+  </input>
+
+  <messages period="0.1">
+
+    <message class="datalink" name="RC_4CH" send_always="true">
+      <!-- manual if you press both left and right shoulder buttons, only one: auto1, none: auto 2 -->
+      <field name="mode" value="2 - LB - RB"/>
+      <field name="throttle" value="Fit(-throttle,-127,127,0,127)"/>
+      <field name="roll" value="roll"/>
+      <field name="pitch" value="pitch"/>
+      <field name="yaw" value="yaw"/>
+    </message>
+
+    <message class="ground" name="JUMP_TO_BLOCK" on_event="HatDown(dpad)">
+      <field name="block_id" value="IndexOfBlock('land')"/>
+    </message>
+
+  </messages>
+</joystick>