[idea] Context API

[manzt]

with pygv.Config() as c:

    c.ref("hg19")
    c.locus("chr8:128,750,948-128,751,025")

    with c.track(url, index=".tbi") as t:
        t.name = "foo"
        t.sort(chr="chr8", position=128750986, option="BASE", direction="ASC")

c.browser()