Use RNArtist instead of R2R to avoid overlaps in Rfam templates

[AntonPetrov]

The idea is to run RNArtist on Rfam families, get JSON output, convert it into R2DT templates and then anytime anyone tries to visualise a sequence from that Rfam family, R2DT will draw it in the same layout as the consensus.

RNArtist layouts are superior to R2R because they have fewer overlaps (for example, 18S rRNA can be drawn without any overlaps).