Suggestion: Change the ASCII text format extension

[sbrl]

I've no idea if this is the latest version of the caeser-lisflood software (is it this one? or this repository?), but I've noticed that your documentation states the following:

Make sure the DEM is in ascii (.asc) format.

.asc is actually a file extension commonly used with GNUPG, or GPG for short. I'd suggest changing it to something else so that it doesn't clash.

I'm a PhD student at the University of Hull whose project title is somewhat similar to the aims of caeser-lisflood - so I found it by a recommendation from my supervisor.