Performance wrapper

Using a wrapper and a 11Mb test BAM file:

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
covtobed example_data/panel_01.bam	555.9 ± 24.9	536.9	611.1	1.00
./covtobed.py example_data/panel_01.bam	612.8 ± 7.8	599.1	624.9	1.10 ± 0.05
cat example_data/panel_01.bam | covtobed	576.7 ± 31.1	553.5	642.0	1.04 ± 0.07
cat example_data/panel_01.bam | ./covtobed.py	654.2 ± 32.6	629.5	719.1	1.18 ± 0.08
./covtobed.pl example_data/panel_01.bam	613.8 ± 8.8	602.3	624.6	1.10 ± 0.05
cat example_data/panel_01.bam | ./covtobed.pl	633.7 ± 12.2	619.9	657.2	1.14 ± 0.06