Minor changes to make project compile with new version of

linear_pendulum_2009/avr/.gitignore

linear_pendulum_2009/avr/Makefile

linear_pendulum_2009/avr/compileUploadCurrentControl.sh

linear_pendulum_2009/avr/compileUploadVelControl.sh

linear_pendulum_2009/avr/current_control.c

linear_pendulum_2009/avr/pccom.c

linear_pendulum_2009/avr/serialio_core.h

linear_pendulum_2009/avr/vel_control.c

linear_pendulum_2009/avr/vel_control.h