make the NewRoute / update pattern api more simple

new route -> try to compile regex in constructor, return error on fail
updatepattern compiles and if success updates patt and regex,
so that we don't have to do that manually in the caller
fix tracking of how many updateConn() are running

reconnecting boolean was out of sync when you update addr via the web ui,
it would cause reconnect to become false when triggered via admin ui,
even if a reconnect was still ongoing triggered by relay()

also, if updateConn errored, it would just return and the reconnecting
bool would be stuck forever

now we use a channel to keep track of how many updateConn's are running,
irrespective from where they are invoked
update old comment, we have spooling now
refactor Route attributes

make the attributes clearer,
and also make the copy operation more explicit
bugfix: don't try to read from spool when spooling disabled
200MB seems better as a default size