NACHO 0.5.5

Minor improvements and fixes

• In R/summarise.R, put example in if (interactive()) {...} instead of \dontrun{...}.
• In R/normalise.R, put example in if (interactive()) {...} instead of \dontrun{...}.
• In R/visualise.R, put example in if (interactive()) {...} instead of \dontrun{...}.
• In DESCRIPTION and README, description updated for CRAN, by adding "messenger-RNA/micro-RNA".