Move canvas implementations

Author: mrkn

lib/unicode_plot.rb

@@ -9,12 +9,6 @@
 require 'unicode_plot/renderer'
 
 require 'unicode_plot/canvas'
-require 'unicode_plot/braille_canvas'
-require 'unicode_plot/density_canvas'
-require 'unicode_plot/lookup_canvas'
-require 'unicode_plot/ascii_canvas'
-require 'unicode_plot/dot_canvas'
-require 'unicode_plot/block_canvas'
 
 require 'unicode_plot/plot'
 require 'unicode_plot/grid_plot'

lib/unicode_plot/canvas.rb

@@ -169,3 +169,9 @@ def lines!(x, y, color = :normal)
     end
   end
 end
+
+require_relative 'canvas/ascii_canvas'
+require_relative 'canvas/block_canvas'
+require_relative 'canvas/braille_canvas'
+require_relative 'canvas/density_canvas'
+require_relative 'canvas/dot_canvas'

lib/unicode_plot/ascii_canvas.rb lib/unicode_plot/canvas/ascii_canvas.rblib/unicode_plot/ascii_canvas.rb renamed to lib/unicode_plot/canvas/ascii_canvas.rb

@@ -1,3 +1,5 @@
+require_relative 'lookup_canvas'
+
 module UnicodePlot
   class AsciiCanvas < LookupCanvas
     ASCII_SIGNS = [