title: Gigantic arrow heads when plotting network with igraph
body: <p><strong>EDIT</strong>
  I was trying to figure out what is wrong with my code and I started to plot simple graphs to see how the arrow will look on smaller graphs. I tired the following command: </p>
  
  <pre><code> g2 &lt;- graph( edges=c(1,2, 2,3, 3, 1), n=10 ) 
   plot(g2)   
  </code></pre>
  
  <p>And here is my graph: <a href="https://i.stack.imgur.com/m1UVl.png" rel="noreferrer"><img src="https://i.stack.imgur.com/m1UVl.png" alt=""></a>. Thus, I think the problem is not with my code but either with igraph or R. I re-installed both, igraph and R but it did not solve the problem. Is it possible that there is a conflict of packages that leads to this? Here is a lit of packages that I have installed:</p>
  
  <pre><code> [1] "base"         "boot"         "class"        "cluster"     
   [5] "codetools"    "colorspace"   "compiler"     "datasets"    
   [9] "dichromat"    "digest"       "doParallel"   "foreach"     
  [13] "foreign"      "graphics"     "grDevices"    "grid"        
  [17] "gridBase"     "gtable"       "igraph"       "irlba"       
  [21] "iterators"    "KernSmooth"   "labeling"     "lattice"     
  [25] "lazyeval"     "magrittr"     "MASS"         "Matrix"      
  [29] "methods"      "mgcv"         "munsell"      "nlme"        
  [33] "NMF"          "nnet"         "parallel"     "pkgmaker"    
  [37] "plyr"         "RColorBrewer" "Rcpp"         "registry"    
  [41] "reshape2"     "rngtools"     "rpart"        "scales"      
  [45] "spatial"      "splines"      "stats"        "stats4"      
  [49] "stringi"      "stringr"      "survival"     "tcltk"       
  [53] "tibble"       "tools"        "utils"        "xtable"    
  </code></pre>
  
  <hr>
  
  <p>I am trying to generate a plot of a network and for some reason I my arrowheads look like small rectangles instead of the usual triangle arrowheads. </p>
  
  <p>Here is the code I am using for my plots:</p>
  
  <pre><code>toy.edges &lt;- na.omit(read.csv("Data/Edge_list-toy.csv", header = TRUE, colClasses = "numeric", na.strings = c("NA", "", "#N/A")))
  toy.nodes &lt;- na.omit(read.csv("Data/NodesDataF-toy.csv", header = TRUE, na.strings = c("NA", "", "#N/A")))
  toy.graph &lt;- graph_from_data_frame(toy.edges, directed = TRUE, vertices = toy.nodes)
  
  V(toy.graph)$color &lt;- "magenta" 
  V(toy.graph)$shape &lt;- "sphere"
  V(toy.graph)$size &lt;- 3*15^(ifelse(is.na(V(toy.graph)$node.size), 0.001, 
  V(toy.graph)$node.size))
  plot(toy.graph, layout = layout.fruchterman.reingold(toy.graph),
       vertex.label=NA, edge.width=E(toy.graph)$weight, 
       edge.arrow.size=0.005, edge.arrow.width=0.0000001)
  </code></pre>
  
  <p>And here is an example plot:</p>
  
  <p><a href="https://i.stack.imgur.com/nghfY.png" rel="noreferrer"><img src="https://i.stack.imgur.com/nghfY.png" alt="[1]: https://i.stack.imgur.com/iCx"></a></p>
  
  <p>It looks even worse when I take slightly bigger values for <code>edge.arrow.size</code> 
   and <code>edge.arrow.width</code>. </p>
  
  <p>What is wrong with my code? Can it have something to do with the version of R? I made a ton of plots before, using very similar command, and I never had problems.</p>
  
  <p>Here are files with <a href="https://www.dropbox.com/s/gp1ec04g5brt19s/NodesDataF-toy.csv?dl=0" rel="noreferrer">nodes info</a> and <a href="https://www.dropbox.com/s/ricg41rplqdc5cj/Edge_list-toy.csv?dl=0" rel="noreferrer">edge list</a>.</p>