Minor grammar fixes.

Author: gedeschaines

tutorial2arm.py

@@ -7,7 +7,7 @@
 # File: tutorial2arm.py
 # Auth: Gary E. Deschaines
 # Date: 5 July 2015
-# Prog: Tutorial on two-link planar 2R robotic arm dynamics with PyODE
+# Prog: Tutorial on two-link planar 2R robotic arm dynamics with ODE
 #       and Pygame.
 # Desc: Models numerical solution for robot dynamics example presented
 #       in section 11.6 of reference [1] listed below.
@@ -16,7 +16,7 @@
 # planar 2R robotic manipulator as articulated body solids modeled with
 # Open Dynamics Engine (ODE) using torques calculated by iteratively
 # solving a state space representation of the dynamic equations of motion
-# forthe modeled system as derived by Newton-Euler recursion.
+# for the modeled system as derived by Newton-Euler recursion.
 #
 # Original basis for this program was obtained at
 #