Fixes #6

/lib/lsb/init-functions exists on Redhat system, but
/etc/init.d/functions does not on Debian-based systems, so
this should work better out-of-the-box.

Fixes #7

This is an ongoing effort to allow different file system layouts (#5)

working on issue #4

Otherwise, excluded domains might be silently ignored.

This obfuscates the error message too much.

Also, distinguish between script name and binary name (#4)

Thanks to @timeos for the initial version (#4)

Apparently, CMake versions < 2.8 expect the FILES keyword in the
file(INSTALL) command.

Update main.cf.ex

Update README.md

Useful for subdomains which are handled by the same
mail server.

The secrets file is now parsed line by line, and
each line (excluding CR and/or LF) is used as a secret.
Only the first secret is used for signing, but all
secrets are used for verification.

This is purely cosmetic.

This eliminates a warning about a missing return
statement. The code was correct though, because
hex2num() is guarded by is_hexdigit().

This is in preparation for future parameters which
may contain whitespaces.

Currently supported are Upstart and System-V.

This file may contain customized configuration options
which should not be overwritten on install.