Create an option in assemble_amplicons.py stage to state min contig length

[kmgibson]

Create an option in assemble_amplicons.py stage for user to state the minimum contig length in alignutils.py in the mummer, show-tiling command.

Line 331: cmd3 = ['show-tiling', '-a', '-i', '%.1f' % 0.6, '-l', '%d' % 200, ------> make an option '-v', '%.1f' % 60, out_fil, '>', out_til, ]

[mlbendall]

You need to add the option to the argparser section and add as a parameter to the function call