A version number is required for npm compliance

Otherwise it throws impossible to understand errors.
Run correctly on OSX

There, a socket may shutdown before the os chooses to do so,
causing a socket error (errno 57). After searching the web, the
easiest workaround is the check of errno done here.

Also: do part of #23, calling render_wikitext instead of local
render. This should mean that tiddlywiki text can include other
types (like markdown).
Get working with node 8.x

In that, httpClient is replaced by http.request

This is part of cleaning up and clarifying to make some
feature improvements.