add input file list method to bamtools merge
add input file list method to bamtools merge

By using -list users can specify a file list.  Workaround for the case
when there are more input files than allowed by the maximum number of
command-line arguments.

kdmurray91/bamtools,boratonAJ/bamtools,pezmaster31/bamtools,kdmurray91/bamtools,sksaskrobinsons/code,iontorrent/bamtools,iontorrent/bamtools,pezmaster31/bamtools,pezmaster31/bamtools,sksaskrobinsons/code,domibel/bamtools,SANBI-SA/bamtools,pezmaster31/bamtools,domibel/bamtools,boratonAJ/bamtools,SANBI-SA/bamtools