[slime-devel] a different flashing function for `slime-compile-region'

Hello, This patch to slime.el makes the `slime-compile-region' flash a more subtle effect. I'm using it, and thought that someone else might enjoy it as well. Maybe a cleaner implementation would be to call a `slime-flashing-function', to allow different flashing styles to be changed more easily. -- "Cut your own wood and it will warm you twice"