Improvement of Rubella::Output::ASCII

I've fixed a bug, which causes, the 11 than 10 lines tho the outputted data.
Now the empty line at the end is removed.
Corresponding to the base class create now returns self.
I also added some documentation.

lib/rubella/output/ascii.rb

@@ -3,10 +3,29 @@ require "rubella/output/base"
 module Rubella
   module Output
 
+    # Creates a ascii art representation of the given storage data.
+    # In @data will a ordenary String be stored. Print the String to your
+    # output field and it will shows a nice ascii art graphic.
+    # There are also different ascii art themes available. Including the
+    # possibility to add own themes.
+    # You only need to push an Array within 10 chars for the representation
+    # into the :symbols Hash. Then you can select it with set the used_symbols
+    # variable to you theme name.
+    #
+    # TODO Use setted field_size for representation
+    #
     class ASCII < Base
       attr_accessor :symbols
       attr_reader   :used_symbols
 
+      # Constructor
+      # Sets the default field_size to 1.
+      # Also sets the used ascii art theme to "shades_ascii". See the
+      # used_symbols= for further information.
+      #
+      # @param field_size int Used chars for one value
+      # @return Rubella::Output::ASCII
+      #
       def initialize field_size = 1
         @symbols = Hash.new
         @symbols["shades"]       = 
@@ -22,6 +41,17 @@ module Rubella
         super field_size
       end
 
+      # Sets the used ascii theme by the given name.
+      # The theme must exist. You can also choose your custom theme here.
+      # The at default avaliable themes are:
+      #   * shades
+      #   * shades_ascii
+      #   * ascii
+      #   * numbers
+      #
+      # @param value String The theme name
+      # @raise ArgumentError
+      #
       def used_symbols= value
         if @symbols.has_key? value
           @used_symbols = value
@@ -31,6 +61,11 @@ module Rubella
           @symbols.keys.join(", ")
       end
 
+      # Creates an ascii art representation of the given storage data.
+      #
+      # @param storage Rubella::Storage
+      # @return Rubella::Storage::ASCII
+      #
       def create storage
         buckets = storage.data[0].length
         # columns = storage.data.length
@@ -41,7 +76,7 @@ module Rubella
 
         # start drawing the damn thing
         ascii_arr = [] 
-        0.upto(buckets).each { |i| ascii_arr[i] = "" }
+        0.upto(buckets-1).each { |i| ascii_arr[i] = "" }
 
         storage.data.each do |point|
           i = 0
@@ -60,6 +95,7 @@ module Rubella
         end
 
         @data = ascii_arr.join("\n")
+        self
       end
     end