Fixes/changes:
Bypassed FreeDOS bug witth findfirst.
Fixed processing of varname in commandline.

New features:
prompt: new meta $e - prints errorlevel
-P will execute dog in the current directory (ie root on boot)
   That is why it is suggested that DOG.COM doesn't exist there.
It is possible to use %envname% in the commandline, and in dog-files, and in
prompt.