updated the dot and pdf in exercise 1, added dot and pdf in exercise 3

...cises/solutions/1_control_flow/f1_pitstop_par_correct.dot

...cises/solutions/1_control_flow/f1_pitstop_par_correct.pdf

...ises/solutions/3_files_and_commands/image_reconstruct.dot

...ises/solutions/3_files_and_commands/image_reconstruct.pdf

...ons/3_files_and_commands/image_reconstruct_scripttask.dot

...ons/3_files_and_commands/image_reconstruct_scripttask.pdf