Address `devtools::check()` warning and note

[jamesmbaazam]

When you run devtools::check(), you get the following warning and note that should probably be addressed:

❯ checking S3 generic/method consistency ... WARNING
  as.igraph:
    function(x, ...)
  as.igraph.epicontacts:
    function(x)
  See section ‘Generic functions and methods’ in the ‘Writing R
  Extensions’ manual.

❯ checking dependencies in R code ... NOTE
  Namespace in Imports field not imported from: ‘colorspace’
    All declared Imports should be used.

• The first is because the as.igraph.epicontacts() is missing a ... like in its generic.

• For the second, it appears colorspace is declared as an import but not used anywhere.

• There is also a requirement for Encoding: UTF-8 in DESCRIPTION.

I will submit a PR to address these issues.

[finlaycampbell]

Thanks for picking up on this! The as.igraph.epicontacts check warning should have been addressed here (ecd721e67aacec15eb36645da9f1035ef89ae6ff), so I'm not sure why you're still seeing it...

[jamesmbaazam]

Strange. Is it probably a devtools bug?