fix: add track offset for segment separators

[msdyachkova]

Fix segment separator positioning when track offset is not 0 (track_align_type is not "left")

[moshi4]

Hi @msdyachkova,

Thanks for the bug fix PR. I'll merge it soon.

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Code for checking bug fix

from pygenomeviz import GenomeViz
from pygenomeviz.parser import Genbank
from pygenomeviz.utils import load_example_genbank_dataset, ColorCycler
ColorCycler.set_cmap("tab10")

gbk_files = load_example_genbank_dataset("saccharomyces")
gbk_list = list(map(Genbank, gbk_files))

gv = GenomeViz(fig_track_height=0.7, feature_track_ratio=0.15, track_align_type="center")
gv.set_scale_bar(ymargin=2.0)

for gbk in gbk_list:
    color = ColorCycler()
    track = gv.add_feature_track(gbk.name, gbk.get_seqid2size(), space=0.01, label_kws=dict(color=color))
    track.set_label(track.name.replace("_", "\n"))
    for segment in track.segments:
        segment.add_feature(segment.start, segment.end, plotstyle="bigrbox", fc=color, lw=0.5)
    track.set_segment_sep()

gv.savefig("result.png")

Before

After