Simplify generation of random numbers
Simplify generation of random numbers

Use the Bash $RANDOM variable to generate random numbers,
rather than just using multiples of the current time.
This yields simpler code, and doesn't fail in timezones
east of UTC. With thanks to Renato Weiße.

salilab/allosmod-lib,salilab/allosmod-lib,salilab/allosmod-lib,salilab/allosmod-lib,salilab/allosmod-lib