Add Joust to preloaded Apps

We currently don't have any games in the preloaded games, lets fix it!

After publishing 'Joust' to the app store I've seen it played by people without my prompting twice, and it's a group game so getting everyone to install it is a huge barrier to entry.

We should make it a phenomenon for tomorrow night!

CC: @rahix (who was in the room when I mentioned this)

preload/apps/joust/__init__.py

+# card10 Joust
+# based on https://github.com/adangert/JoustMania
+
+import display
+import os
+import utime
+import buttons
+from color import Color
+import leds
+import vibra
+import bhi160
+
+COLOR_GREEN = (0, 255, 0)
+COLOR_RED = (255, 0, 0)
+COLOR_ORANGE = (255, 125, 0)
+COLOR_WHITE = (255, 255, 255)
+
+ACCELEROMETER = bhi160.BHI160Accelerometer()
+
+
+class JoustSensor:
+    NUM_READINGS = 1
+
+    def __init__(self):
+        self.sensor = ACCELEROMETER
+        self.last_accels = []
+        self.jerk = 0.0
+        self.threshold = 1.8
+
+    def get_jerk(self):
+        readings = list()
+        while not readings:
+            readings = self.sensor.read()
+            if len(readings) > 0:
+                self.last_accels = self.last_accels + readings
+                self.last_accels = self.last_accels[-JoustSensor.NUM_READINGS :]
+                jerk_x = sum([a.x for a in self.last_accels]) / JoustSensor.NUM_READINGS
+                jerk_y = sum([a.y for a in self.last_accels]) / JoustSensor.NUM_READINGS
+                jerk_z = sum([a.z for a in self.last_accels]) / JoustSensor.NUM_READINGS
+                self.jerk = (jerk_x ** 2 + jerk_y ** 2 + jerk_z ** 2) ** 0.5
+        return self.jerk
+
+    def too_fast(self):
+        return self.get_jerk() > self.threshold
+
+
+def wait_button():
+    utime.sleep_ms(1000)
+    while True:
+        pressed = buttons.read(buttons.BOTTOM_LEFT | buttons.BOTTOM_RIGHT)
+        if pressed != 0:
+            break
+    if pressed & buttons.BOTTOM_LEFT != 0:
+        return "BL"
+    if pressed & buttons.BOTTOM_RIGHT != 0:
+        return "BR"
+    if pressed & buttons.UPPER_RIGHT != 0:
+        return "BR"
+    if pressed & buttons.UPPER_LEFT != 0:
+        return "UL"
+    return "??"
+
+
+def joining_game():
+    set_display("JOIN ?", COLOR_WHITE)
+    set_color(COLOR_WHITE)
+
+
+def status_in_game():
+    set_display("IN GAME", COLOR_GREEN)
+    set_color(COLOR_GREEN)
+
+
+def status_out_game():
+    set_display("DROPPED", COLOR_RED)
+    set_color(COLOR_RED)
+
+
+def set_display(text, colr):
+    with display.open() as disp:
+        disp.clear()
+        disp.print(text, fg=colr, bg=(0, 0, 0), posx=30, posy=30)
+        disp.update()
+
+
+def set_color(colr):
+    for i in range(15):
+        leds.prep(i, colr)
+    leds.update()
+
+
+def countdown(n):
+    colr = COLOR_WHITE
+    for i in range(n, 0, -1):
+        if i == 3:
+            colr = COLOR_RED
+        elif i == 2:
+            colr = COLOR_ORANGE
+        elif i == 1:
+            colr = COLOR_GREEN
+        set_display("START: %d" % i, colr)
+        leds.clear()
+        vibra.vibrate(300)
+        utime.sleep_ms(1000)
+    vibra.vibrate(1000)
+
+
+def change_status(status):
+    status()
+    vibra.vibrate(1000)
+
+
+def run():
+    print("Starting ...")
+    acc = JoustSensor()
+    i = 0
+    states = [joining_game, status_in_game, status_out_game]
+    while True:
+        current_status = states[i % len(states)]
+        change_status(current_status)
+        i += 1
+        if current_status == joining_game:
+            wait_button()
+            countdown(5)
+        elif current_status == status_in_game:
+            while not acc.too_fast():
+                pass
+        elif current_status == status_out_game:
+            wait_button()
+
+
+run()