Ported text command over to the new args classes

* Involved a big rewrite of arg_loader to accomodate nil and false better. Sadly this meant dumping ||= for if-statements. Blech, but works.
  * Updates to regression tests are pretty trivial.
  * Removed graphics_text_spec because, even though it looks useful, with rake sanity it really isn't.
  * Exposed font on deck as well

Cleaned up graphics/text.rb too!

spec/api/api_text_spec.rb

@@ -1,37 +0,0 @@
-require 'spec_helper'
-require 'squib'
-
-describe Squib::Deck, '#text' do
-
-  context 'fonts' do
-     it "should use the default font when #text and #set_font don't specify" do
-      card = instance_double(Squib::Card)
-      expect(card).to receive(:text).with(anything, 'a', 'Arial 36', *([anything] * 17)).once
-      Squib::Deck.new do
-        @cards = [card]
-        text str: 'a'
-      end
-    end
-
-    it "should use the #set_font when #text doesn't specify" do
-      card = instance_double(Squib::Card)
-      expect(card).to receive(:text).with(anything, 'a', 'Times New Roman 16', *([anything] * 17)).once
-      Squib::Deck.new do
-        @cards = [card]
-        set font: 'Times New Roman 16'
-        text str: 'a'
-      end
-    end
-
-    it 'should use the specified font no matter what' do
-      card = instance_double(Squib::Card)
-      expect(card).to receive(:text).with(anything, 'a', 'Arial 18', *([anything] * 17)).once
-      Squib::Deck.new do
-        @cards = [card]
-        set font: 'Times New Roman 16'
-        text str: 'a', font: 'Arial 18'
-      end
-    end
-  end
-
-end