variable: log-default-route
procedure: log-message categories arguments ... ->
symbol/(symbol ...) any ... ->
filters log-routes and calls any matching log-route formatter with arguments.
categories can be a tree-like list with prefixed symbols and/or/not.
log-route: #(symbol/(symbol ...) procedure:{list list ->} (port:output-port ...))
procedure: log-routes-set! a ->
variable: sph-log-description