Resolve "Add option to use light travel times instead of proper pseudo ranges"

Closes #25 (closed)

• Add a parameter neglect_tps to read tcb/t, tcb/tt and tcb/d_tt instead of tps/tau, tps/ppr and tps/d_ppr
• Refactor orbit file reading (v1.0, 1.0.1 or 1.0.2) into its own function