Split up the plugin implementation into two classes: one for markup templates (?genshi-markup? or just ?genshi?) and one for text templates (?genshi-text?). Also added an example for plain-text templating to the TurboGears example app.

new file mode 100644
--- /dev/null
+++ b/examples/turbogears/genshitest/templates/plain.txt
@@ -0,0 +1,8 @@
+#choose
+  #when name
+    Hello, $name!
+  #end
+  #otherwise
+    Hello, anonymous!
+  #end
+#end