Add read count (RC) attribute to GFA [feature request]

[sjackman]

Bandage will draw the thickness of the unitig segments according to their depth when the segments include the read count (RC:i) attribute.
See https://github.com/GFA-spec/GFA-spec/blob/master/GFA1.md#optional-fields-2

[sjackman]

Somewhat related, is the fourth field of the x records the number of read susbtrings used to build the unitig segment? Does Miniasm output somewhere the total number of reads involved in a unitig, not just those reads used to compose the final sequence?

x       utg003137l      21310   5

[sjackman]

Unicycler outputs the scaled depth of coverage in the dp:f: tag, for example dp:f:1.50 is 50% more depth than a typical sequence.