[Xymon] Core dump in showgraph.cgi with very large "service" name

One more bug that I can't track down where to fix. If I go to a "showgraph" page and change the "service" value to something ludicrously large (2k or more), then showgraph.cgi dumps core.

Fixed now. I've done a code audit of the web CGI's today, and fixed a bunch of potential problems with parameter handling.

I need to do some more testing to make sure it hasn't broken anything. After that, there will be a 4.3.4 release.

Regards, Henrik