Add optional width and height arguments save plots

Sometimes the graphs must have a special size. This adds optional
arguments for width and height.

utils.R

@@ -11,9 +11,9 @@
 # or NULL if not needed.
 # Default filesize is 3000x3000 px and 300 dpi resolution.
 #
-sma_plot_file <- function(fname, ftype, fun) {
+sma_plot_file <- function(fname, ftype, fun, width = 3000, height = 3000) {
 	# Open file for writing
-	ftype(filename = fname, width = 3000, height = 3000, res = 300)
+	ftype(filename = fname, width = width, height = height, res = 300)
 
 	#
 	# Write plot into variable, then printing it manually. This is