Bump rustbio version. Closes #8.

bed3 parsing was broken in older versions of rustbio. Now resolved with
latest version.

Change hint on bed format to indicate correct bed4.

v0.3.42 Data Viz Update

* Added --html flag which writes interactive vplot heatmaps in html
format following data export rules defined in --multi.

Update README with dataviz examples.

add hint about indexing bam file if missing.

Release v0.3.4.

* The 0.3 series of `vplot` introduces a breaking change for matrix
formatting. Matrices are now returned such that large fragments are at
the top. This can be reverted using the `-i` flag to invert the matrix
to have small fragments at the top instead (pre-0.3 behavior).

* `-o` flag for writing to a file path.

* the `--multi` flag writes matrices for each region in the input bed
file. An optional prefix or ouput directory can be added using the `-o`
flag.

changed default behavior so that largest fragments are at the top.

Revert by setting -i. Closes #9.

fix versions.

-o flag now implemented. Closes #7.

Fix coordinates.