Add SIM_lander README to explain what it is, and how to use. REF#997

trick_sims/SIM_lander/README.md

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+# SIM_lander
+![Graphics CLient Showing Lander on the ground](images/Lander.png)
+
+
+SIM_lander simulates a lunar lander, with manual and automatic controls.
+
+### Building the Simulation
+In the SIM\_lander directory, type **trick-CP** to build the simulation executable. When it's complete, you should see:
+
+```
+=== Simulation make complete ===
+```
+Now **cd** into models/graphics/ and type **make**. This builds the display client for the simulation.
+
+### Running the Simulation
+In the SIM_lander directory:
+
+```
+% S_main_*.exe RUN_test/input.py
+```
+The Sim Control Panel, and a GUI called "Lander Range" should appear.
+
+Click the Start on the Trick Sim Control Panel.
+
+![Graphics CLient Showing Lander on the ground](images/LanderInitial.png)
+
+Using the controls shown below have fun!
+
+
+
+![Graphics CLient Showing Lander on the ground](images/ManualControlPanel.png)
+
+![Graphics CLient Showing Lander on the ground](images/AutomaticControlPanel.png)
+
+## Initial Conditions
+To set the initial state of the lander, edit the following variables in the input file.
+
+Variable                                  | Type           | Units
+------------------------------------------|----------------|-------
+dyn.lander.pos                            | double[2]      | m
+dyn.lander.vel                            | double[2]      | m
+dyn.lander.angle                          | double         | rad
+dyn.lander.angleDot                       | double         | rad/s