Meta dot should work on namespaces

I'm using 2 different methods of resolving a namespace's file. One is if the symbol can be found in the `ns-aliases` of the current `ns` in which case you need to resolve it through there. Two is if it's a fully qualified namespace in which case you can just use `find-ns`. In either case you have to get the meta of one of it's public symbols AFAICT because namespaces do not include metadata on where they were declared.

I'm cheating as far as where the `ns` declaration is found. It's idiomatic to place it on the first line of the file but it might not be. In any event this will still get you to the file the namespace was declared in most of the time, even if you're not on the line itself.

Finally, I removed the `search-forward-regex` call as it's unnecessary unless that brief flash desired. There's no good thing to search forward for if you're going to support more than the lookup of vars.

This would close [issue #239](https://github.com/kingtim/nrepl.el/issues/239).