Avoid grep ambiguities

Where regular expression is read from a variable and -e argument is not
provided, the resulting call may end up being interpreted as grep
argument.

See also:

    https://github.com/koalaman/shellcheck/issues/1342

src/imapdomo.skel

     # Handle action $Action
     #
     local cmd       # imapfilter command
-    lshandlers | grep -qw "$Action" || {
+    lshandlers | grep -qwe "$Action" || {
         warn "no handler for action: $Action.lua in $CfgDir/handlers"
         return 2
     }