Extract typefactory converter from CLI

CMakeLists.txt

@@ -15,6 +15,8 @@ function(kindle2latex_enable_warnings target)
 endfunction()
 
 add_executable(kindle2latex_typefactory
+  typefactory/converter.cpp
+  typefactory/converter.h
   typefactory/main.cpp
   typefactory/typefactory.h
 )