Execute the smoothing multiple times

[AndreaGuarracino]

• [x] make the smoothing iterable
• [x] generalize -l|--poa-length-target for multiple values
• [x] add mandatory argument -r|--n-haps so that we calculate w|--block-weight-max automatically if it was not set. see https://github.com/pangenome/pggb/blob/0c774c97cca2433d3d070895df362f0d5da244e4/pggb#L532.
• [x] Update stderr messages so that we know in which iteration we are in.
• [x] testing
• [ ] OPTIONAL: reduce the I/O burden by keeping a single graph in memory from start to end. FUTURE FEATURE, as it requires a different management of the XG/ODGI/GFA

[subwaystation]

If I just run

smoothxg       -t 16       -T 16       -g DRB1-3123.fa.gz.seqwish.gfa       -r 12                     -X 100       -I 0.7       -R 0       -j 0       -e 0       -l 700,900,1100       -P 1,19,39,3,81,1       -O 0.001       -Y $(echo "100 * 12" | bc)       -d 0 -D 0       -S              $maf_params       -V       -o DRB1-3123.fa.gz.smoothxg.gfa

I get

...
[smoothxg::(2-3)::prep] writing graph /DRB1-3123.fa.gz.seqwish.gfa.smooth.0.gfa.prep.1.gfa
[smoothxg::(2-3)::main] building xg index
smoothxg_: /home/heumos/git/smoothxg/deps/gfakluge/src/gfakluge.hpp:571: size_t gfak::mmap_open(const std::string&, char*&, int&): Assertion `false' failed.
Aborted (core dumped)

I figured if one just provides the file name there is a / prepended to the prepped graph. In progress of fixing.