plotTxModels: Plot transcript models.
In KasperThystrup/circulaR: Characterization of circRNAs from Total RNA-seq data

Using data stored in an EnsDB from AnnotationHub.

1	plotTxModels(db = NULL, g = NULL, tid = NULL, showDirection = T, rangex = NULL)

`db`	A db containing transcript models from AnnotationHub/Ensembl.
`g`	Specify which gene to plot (Ensembl Gene ID).
`showDirection`	Boolean indicating wheter to add chevrons to intronic regions to indicate direction of the transcript.
`rangex`	The range in genomic coordinates for the region of interest. This is important for correct alignment of the tx model plot with splice junction plot.