[FR] Add option to pad resulting file

[malvarenga123]

As described here, here and here, OPL and hdl-dump cannot handle ZSO files with a size that is not a multiple of 2048. ZISO Compressor fixed this with the -h option. It would be handy if maxcso had an option to pad the file with zeroes to the next multiple defined by the user (like the --block argument).