Pango scaling of "spacing" in text is done once

Spacing also defaults to nil, not zero, as before

Fixes #98

lib/squib/args/paragraph.rb

@@ -17,7 +17,7 @@ module Squib
           justify:   false,
           wrap:      true,
           ellipsize: :end,
-          spacing:   0,
+          spacing:   nil,
           valign:    :top,
           hint:      :off
         }
@@ -98,7 +98,7 @@ module Squib
       def validate_spacing(arg, _i)
         return nil if arg.nil?
         raise ArgumentError, 'spacing must be a number or nil' unless arg.respond_to? :to_f
-        Pango::SCALE * arg.to_f
+        arg.to_f * Pango::SCALE
       end
 
       def validate_valign(arg, _i)
@@ -112,4 +112,4 @@ module Squib
     end
 
   end
-end
+end

lib/squib/graphics/text.rb

@@ -143,7 +143,7 @@ module Squib
         layout.alignment = para.align
 
         layout.justify = para.justify unless para.justify.nil?
-        layout.spacing = para.spacing * Pango::SCALE unless para.spacing.nil?
+        layout.spacing = para.spacing unless para.spacing.nil?
         cc.update_pango_layout(layout)
 
         embed_draws    = process_embeds(embed, para.str, layout)