Create routenames pkg for better reusability

[leomorpho]

Originally, route names were defined in routes package. That was problematic as the variables pointing to the string literals could not be used in templates, and hence we had to use the string literals in the templates. This increased friction on maintainability (one could change the string literal in the routes package and hence break any usage in the pages package (if not careful, which has happened to me before...).

Now, the route names can be used as routenames.X throughout the code, improving maintainability and decreasing the changes to inadvertently break old routes.