add initial version of SimpleScene used for communcation with CeTI

interfaces/SimpleScene/SimpleScene.proto

+syntax = "proto3";
+
+message IposConfig {
+    repeated IposFrame frame = 1;
+    repeated IposObject object = 2; // an object must be either in this list
+    repeated IposObjectConfig objectConfig = 3; // or in this list, not in both
+}
+
+message IposObjectConfig {
+    string id = 1; // unique for each object, but there may be multiple positioning sensors for that object
+    string sensorId = 2; // unique (each sensor localizes a single object)
+    string type = 3; // CeTI will send BOX,BIN,ZONE,ROBOT,HUMAN,OTHER
+}
+
+message IposPositionUpdate {
+  repeated IposObject object = 1;
+}
+
+message IposObject {
+  string id = 1; // unique for each object, but there may be multiple sensors
+  string sensorId = 2; //unique
+  string type = 3; // Applications may send BOX,BIN,ZONE,ROBOT,HUMAN,OTHER
+  IposRelativePosition position = 4;
+  IposSimpleOrientation orientation = 5;
+  string lastPosUpdate = 6; // https://en.wikipedia.org/wiki/ISO_8601
+}
+
+message IposFrame {
+  string id = 1; // unique for every frame, used for relative coordinates
+  IposSpace space = 2; // cube defining the extension, might be (0,0,0)
+  IposPosition position = 3; // centre of the "frame" cube, absolute
+  float delta = 4; // min. Position to trigger a position update
+}
+
+// relative coordinates
+message IposRelativePosition {
+  string IposFrame_id = 1;
+  IposPosition pos = 2;
+}
+
+// relative coordinates
+message IposPosition {
+  float x = 1; // pos in x direction in m
+  float y = 2; // pos in y direction in m
+  float z = 3; // pos in z direction in m (up)
+  float accuracy = 4; // object is with 95% probability within x metres of this point (gaussian distribution)
+}
+
+message IposSpace {
+  float x = 1; // size in x direction in m
+  float y = 2; // size in y direction in m
+  float z = 3; // size in z direction in m (height)
+}
+
+message IposSimpleOrientation {
+  float x = 1; // quaternion notation
+  float y = 2; // if the quaternion is (0,0,0,0)
+  float z = 3; // there is no orientation
+  float w = 4; // available
+}