deal with page management better

[meganrm]

          suggestion: create a Pages.ts module, hardcode symbolic names for each page and keep the numbers only in that module.  It could be an enum or a class or just a bunch of constants or whatever. Pages.ts can have things like nextPage(PAGE_FOO) and stuff like that, as needed.  Import Pages.ts everywhere....

Originally posted by @toloudis in #137 (comment)