Add support for other paper sizes

Hi! I live in the US, and needed support for Letter paper in my printer. Before I patched the filter, all my printer would do was hum a bit and then light the Alert LED. It gave no other indication on what could be wrong.

I imagine that a great deal of the “it doesn't work” bug reports against this project is from Americans who do not understand what the “A4” in the list of current restrictions is. Very few people here are familiar with A4, A5 etc.

It's hard to test other sizes, but it seems to me that the names used in CUPS correspond reasonably well with PCL, except that the RICOH requires the name to be in uppercase. I have therefore chosen to simply uppercase the names, hoping that this would also make the untested sizes work.

Thanks,
Knut Auvor Grythe