Redesigning how config files are read, stored, and delegated

With the new design, we take the load off of deck.rb and simply delegate methods over to the new conf.rb. This means that things like `antialias` is now available as a method to the normal Squib scripts for easy checking (without being mutable). Squib::Conf also handles parsing and defaults, and any potential input validation we need to do in the future.

Typographer is also set up now as a deck-wide configuration. This may change in the future if we want typography customization per-command, although that seems like a strange use case.

Lots of tests for this one, and lots of cross-cutting concerns in this commit.

This commit also includes some tweaks to rspec tests, including tagging of slow tests for a `rake spec_fastonly`

Conflicts:
	spec/samples/samples_regression_spec.rb
	spec/spec_helper.rb
	squib.sublime-project

spec/samples/samples_regression_spec.rb

@@ -13,7 +13,7 @@ describe "Squib samples" do
   end
 
   Dir["#{@SAMPLES_DIR}/**/*.rb"].each do |sample|
-    it "should execute #{sample} with no errors" do
+    it "should execute #{sample} with no errors", slow: true do
       allow(Squib.logger).to receive(:warn) {}
       allow(ProgressBar).to receive(:create).and_return(Squib::DoNothing.new)
       load sample
@@ -68,7 +68,7 @@ describe "Squib samples" do
       tgc_proofs.rb
       units.rb
   ).each do |sample|
-    it "has not changed for #{sample}" do
+    it "has not changed for #{sample}", slow: true do
       log = StringIO.new
       mock_cairo(log)
       load sample