Use "m_include" tag for including link detail template

Each In-Portal module offers 2 basic templates for the items that can be created within that module:

list template - lists all items within a category
detail template - shows details about individual item

The In-Link module has improved that system by allowing an end user to specify (in the CustomTemplate field in database) a per-item detail template override. Technically this is done by placing DisplayDetailTemplate tag into the actual detail template. Then tag will decide whatever the default or the user override template needs to be shown.

Problem is that in that tag, we're processing given template name not via <inp2:m_Include template="..."/> tag, but via <inp2:m_RenderElement name="..."/> tag. In retrospective it turns out that this was very bad idea, when the include template as another m_Include/m_RenderElement tags on it.

Here is a fix: replace ParseBlock with IncludeTemplate on the link_tag_processor.php file, in the DisplayDetailTemplate tag.