A much-needed cleanup of the portification of this code:
Remove PREFIX/modules directory if it doesn't contain other modules;
use static plist (new file: pkg-plist).
Switch to a modern USE_RC_SUBR (moved file: files/est.sh --> files/est.in).
Silence install here and there.
Fix IGNORE message.
IGNORE if no kernel sources installed.
Bump PORTREVISION for plist change.
Submitted by: itetcu (who really needs to get a commit bit soon...)