Allow branch selection when running mergePOOL utility
mergePool -o -i <input-file 1> [ -i <input-file 2> ...] [-e <exclude-tree 1>] -C LZ4/LZMA/ZLIB -B branchfile
input- and output files may consist of any legal file name. -debug Switch debug flag on. branchfile text file with single branchname per line