Study to investigate safety and tolerability of single, inhaled doses (2.5 μg, 5 μg, 10 μg, 20 μg and 40 μg) of BI 1744 CL in free dose combination with tiotropium bromide 5 μg (for doses up to and including 20 μg BI 1744 CL) and 10 μg (for doses of 20 μg and 40 μg BI 1744 CL), both administered by Respimat® in healthy male volunteers. Also, to investigate the pharmacokinetics of BI 1744 BS and tiotropium bromide in such combinations, to explore their dose proportionality, and to explore the pharmacodynamic effects of the treatments on selected metabolic and respiratory parameters