Added xarm7.

Author: Stephen James

pyrep/robots/arms/xarm7.py

@@ -0,0 +1,7 @@
+from pyrep.robots.arms.arm import Arm
+
+
+class XArm7(Arm):
+
+    def __init__(self, count: int = 0):
+        super().__init__(count, 'xarm', 7)

pyrep/robots/end_effectors/xarm_gripper.py

@@ -0,0 +1,13 @@
+from pyrep.robots.end_effectors.gripper import Gripper
+
+
+class XArmGripper(Gripper):
+
+    def __init__(self, count: int = 0):
+        super().__init__(count, 'xarm_gripper',
+                         ['xarm_left_inner_knuckle_joint',
+                          'xarm_right_inner_knuckle_joint',
+                          'xarm_drive_joint',
+                          'xarm_left_finger_joint',
+                          'xarm_right_outer_knuckle_joint',
+                          'xarm_right_finger_joint'])