Add tests and docs for Flap component

docs/Components/Aerodynamic/Flap.md

@@ -0,0 +1,29 @@
+# Flap
+
+The Flap class is intended to be a modifier for the lift and drag calculation on wings. Currently it only has height and width properties that can afterwards be used to calculate its correct aerodynamic behaviour.
+
+## Instantiation
+To instantiate a Flap one can pass the same arguments used to instantiate an AttachedComponent plus its height and width:
+
+``` python
+import math
+from vec import Vector2
+
+from adr.Components.Aerodynamic import Flap
+
+flap = Flap(
+    name='flap',
+    mass=0.05,
+    relative_position=Vector2(-0.34, 0),
+    relative_angle=math.radians(0),
+    width=0.25,
+    height=0.06
+)
+
+print(flap.type)
+>>> flap
+print(f'Flap dimensions are: {100*flap.width} x {100*flap.height} [cm].')
+>>> Flap dimensions are: 25.0 x 6.0 [cm].
+```
+
+Remember that a Flap component represents only one physical flap, so one probably wants to always have at least two simetrically positioned flap instances on each aerodynamic surface.

mkdocs.yml

@@ -7,6 +7,8 @@ nav:
             BaseComponent: Components/BaseComponent.md
             FreeBody: Components/FreeBody.md
             AttachedComponent: Components/AttachedComponent.md
+            Aerodynamic:
+                Flap: Components/Aerodynamic/Flap.md
         World:
             Ambient: World/Ambient.md
             constants: World/constants.md

tests/Components/Aerodynamic/test_Flap.py

@@ -0,0 +1,24 @@
+import pytest
+import math
+from vec import Vector2
+
+from adr.Components.Aerodynamic import Flap
+
+
+@pytest.fixture
+def flap():
+    flap = Flap(
+        name='flap',
+        mass=0.05,
+        relative_position=Vector2(-0.34, 0),
+        relative_angle=math.radians(0),
+        width=0.25,
+        height=0.06
+    )
+    return flap
+
+
+def test_instantiation(flap):
+    assert(flap.type == 'flap')
+    assert(flap.width == 0.25)
+    assert(flap.height == 0.06)