title: Colours don't show up in seqrplot
body: <p>I have a question regarding the seqrplot function in the R TraMineR package which plots sets of representative sequences. I have a big dataset on infringement proceedings with EU law (due to the length of the proceedings, I use the seqgranularity function) and use the following code. </p>
  
  <pre><code>library(TraMineR)
  library(TraMineRextras)
  library(grDevices)
  
  #example data
  directives &lt;-
     structure(list(id = c(891L, 6826L, 9451L, 8816L), country_short = structure(c(2L,1L, 1L, 1L), 
  .Label = c("I", "P"), class = "factor"), year = c(1992L, 1981L, 1980L, 1980L), 
  federal = c(0L, 1L, 1L, 1L), admin = c(5331L, 
  1423L, 735L, 656L), pol = c(NA, NA, NA, 223L), adjud = c(NA, NA, NA, 330L), 
  postlit = c(NA_integer_, NA_integer_, NA_integer_, NA_integer_), 
  ADM = structure(c(2L, 1L, 4L, 3L), .Label = c("(ADM,1423)", "(ADM,5331)", "(ADM,656)", 
  "(ADM,735)"), class = "factor"), POL = structure(c(NA, NA, NA, 1L), .Label = "(POL,223)", 
  class = "factor"), ADJ = structure(c(NA, NA, NA, 1L), .Label = "(ADJ,330)", 
  class = "factor"), PLIT = structure(c(NA_integer_, NA_integer_, NA_integer_, NA_integer_), 
  .Label = character(0), class = "factor")), .Names = c("id", "country_short", "year", "federal", 
  "admin", "pol", "adjud", "postlit", "ADM", "POL", "ADJ", "PLIT"), row.names = c(NA, 4L), class = "data.frame")  
  
  directives.seq&lt;-seqdef(data=directives, var=9:12, xtstep=364, 
                         informat = "SPS", SPS.in=list(xfix="()",sdsep=","),
                         cpal=c("blue","gray","black","green"),
                         void="%", alphabet=c("ADM","POL","ADJ","PLIT"), 
                         labels=c("Administration phase","Political phase","Adjudication phase","Post-litigation phase"))
  directives.seq.month&lt;-seqgranularity(directives.seq, tspan=30, method="first")
  directives.om&lt;-seqdist(directives.seq.month, full.matrix=FALSE, method="OM", indel=1, sm="TRATE")
  seqrplot(directives.seq.month, diss=directives.om, group=directives$federal, criterion="dist", nrep=3)
  </code></pre>
  
  <p>However, the plot does not seem to take into account the colour palette which is attributed to the sequence object. Instead it returns the representative sequences in black <a href="https://i.stack.imgur.com/Y5qXi.png" rel="nofollow noreferrer">(see screenshot)</a>. I checked my par() settings and they seem to be fine since all the other plots are duly coloured. Or is there any way of restoring the default setting of par()? I also tried to run the code with smaller subsamples but it didn't change the result. 
  Does anybody have an idea how to solve this issue? </p>
  
  <p>Thank you very much in advance! </p>