Allow configuration of typographical replacements, e.g. smart quotes

If you're living in a non-UTF-8 character set, then you can configure what quotes are smartly changed.
If my regexes are messing things up, you can also turn this off with smart_quotes: false
Also updated docs.

This closes #50

squib.sublime-project

@@ -24,6 +24,10 @@
 			"name": "rake run[draw_shapes]",
 			"shell_cmd": "rake run[draw_shapes]",
 		},
+		{
+			"name": "rake run[config_text_markup]",
+			"shell_cmd": "rake run[config_text_markup]",
+		},
 		{
 			"name":        "rspec spec/samples/samples_regression_spec.rb",
 			"shell_cmd":   "rspec spec/samples/samples_regression_spec.rb",
@@ -39,6 +43,7 @@
 			"shell_cmd":   "rspec spec/graphics/graphics_text_spec.rb",
 			"working_dir": "${project_path:${folder}}"
 		},
+
 	],
 
 }