Add self-closing support for custom template tags

[hijonathan]

Example:

- mytag
      Add stuff here

compiles to:

{% mytag %}
      Add stuff here
{% endmytag %}

It'd be nice to support these and just assume/require that we adhere to typical django naming conventions (e.g. the closing tag starts with "end").

[bcoughlan]

Are there any scenarios where a tag followed by an indented line shouldn't be self-closing?

[hijonathan]

Yeah, actually this would be a problem for custom one-liner tags.

Example:

- wrap_in_anchor "http://www.example.com"

should compile to:

{% wrap_in_anchor "http://www.example.com" %}

which could then be used to wrap the passed value in a special anchor tag or whatever.

I think there may be a better way to do this, but I haven't quite figured it out yet.