Provide a convenience string overload for connectRedisDB

[wilzbach]

Split-off from #1842

This is inspired by the way mongo handles things, hence the weird underscore parameter name.
I would prefer sth. like hostOrURL though ;-)

[WebFreak001]

This should leave a message what's wrong and why it's wrong for the user because this is a public function.

Something like host must be a valid IP or domain, but not an URI

[wilzbach]

We could also think about parsing the host URL if the user accidentally called the wrong function, but imho it's better to use an error message here, because if the user has a full redis URI, he should have called connectRedisDB which returns a RedisDatabase and not only a RedisClient

[wilzbach]

Added the error message to the assert. Anything else blocking this?

[WebFreak001]

I never use redis (always mongodb) so I'm not sure about how consistent the getDatabase(0) part is with other implementations/apis but otherwise this LGTM as it is a pretty simple change

[wilzbach]

I never use redis (always mongodb) so I'm not sure about how consistent the getDatabase(0)

It's the default database like Mongo's default default.

Anyhow, in case it wasn't clear this just unifies the API with how the analog connectMongoDB works:

vibe.d/mongodb/vibe/db/mongo/mongo.d

Lines 77 to 91 in 892e094

	MongoClient connectMongoDB(string host, ushort port)
	{
	assert(!host.startsWith("mongodb://"));
	return new MongoClient(host, port);
	}
	/// ditto
	MongoClient connectMongoDB(string host_or_url)
	{
	/* If this looks like a URL try to parse it that way. */
	if(host_or_url.startsWith("mongodb://")){
	return new MongoClient(host_or_url);
	} else {
	return new MongoClient(host_or_url, MongoClientSettings.defaultPort);
	}
	}

Ping @s-ludwig