Handle more than 10K CNVkit calls

[pdiakumis]

Currently the graphics device or OmicCircos can't handle more than 40K segments:

> sv <- prep_manta_vcf("COLO829_80pc-batch__COLO829_80pc_EMA-sv-prioritize-manta-filter.vcf")
> cnv <- prep_cnvkit_seg("COLO829_80pc-batch-cnvkit-call.cns")
> plot_circos(sv = sv, cnv = cnv)
Error: vector memory exhausted (limit reached?)

> cnv
$cnv
# A tibble: 82,321 x 4
   chrom   start     end tot_cn
   <chr>   <int>   <int>  <dbl>
 1 1      238901 1475299      2
 2 1     1475557 1511599      1
 3 1     1511599 1645636      2
 4 1     1645737 1655154      3
 5 1     1655255 1669985      2
 6 1     1670095 1686350      1
 7 1     1686350 1771996      2
 8 1     1771996 1798373      3
 9 1     1798373 1814923      2
10 1     1814923 1839386      1
# ... with 82,311 more rows

attr(,"class")
[1] "cnv"

For now let's just output the Manta calls and ignore CNVkit segments.