AABB: Improve docs and test for `has_point`

Contrarily to the 2D Rect2i counterpart, it doesn't make much sense in 3D
and for floating-point AABBs to exclude points on some of its faces.

doc/classes/AABB.xml

@@ -158,14 +158,15 @@
 			<return type="bool" />
 			<argument index="0" name="point" type="Vector3" />
 			<description>
-				Returns [code]true[/code] if the [AABB] contains a point.
+				Returns [code]true[/code] if the [AABB] contains a point. Points on the faces of the AABB are considered included, though float-point precision errors may impact the accuracy of such checks.
+				[b]Note:[/b] This method is not reliable for [AABB] with a [i]negative size[/i]. Use [method abs] to get a positive sized equivalent [AABB] to check for contained points.
 			</description>
 		</method>
 		<method name="intersection" qualifiers="const">
 			<return type="AABB" />
 			<argument index="0" name="with" type="AABB" />
 			<description>
-				Returns the intersection between two [AABB]. An empty AABB (size 0,0,0) is returned on failure.
+				Returns the intersection between two [AABB]. An empty AABB (size [code](0, 0, 0)[/code]) is returned on failure.
 			</description>
 		</method>
 		<method name="intersects" qualifiers="const">

tests/core/math/test_aabb.h

@@ -348,15 +348,28 @@ TEST_CASE("[AABB] Has point") {
 	CHECK_MESSAGE(
 			aabb.has_point(Vector3(2, 3, 0)),
 			"has_point() with contained point should return the expected value.");
+	CHECK_MESSAGE(
+			!aabb.has_point(Vector3(-20, 0, 0)),
+			"has_point() with non-contained point should return the expected value.");
+
 	CHECK_MESSAGE(
 			aabb.has_point(Vector3(-1.5, 3, 0)),
-			"has_point() with contained point on negative edge should return the expected value.");
+			"has_point() with positive size should include point on near face (X axis).");
 	CHECK_MESSAGE(
 			aabb.has_point(Vector3(2.5, 3, 0)),
-			"has_point() with contained point on positive edge should return the expected value.");
+			"has_point() with positive size should include point on far face (X axis).");
 	CHECK_MESSAGE(
-			!aabb.has_point(Vector3(-20, 0, 0)),
-			"has_point() with non-contained point should return the expected value.");
+			aabb.has_point(Vector3(0, 2, 0)),
+			"has_point() with positive size should include point on near face (Y axis).");
+	CHECK_MESSAGE(
+			aabb.has_point(Vector3(0, 7, 0)),
+			"has_point() with positive size should include point on far face (Y axis).");
+	CHECK_MESSAGE(
+			aabb.has_point(Vector3(0, 3, -2.5)),
+			"has_point() with positive size should include point on near face (Z axis).");
+	CHECK_MESSAGE(
+			aabb.has_point(Vector3(0, 3, 3.5)),
+			"has_point() with positive size should include point on far face (Z axis).");
 }
 
 TEST_CASE("[AABB] Expanding") {