This function returns the content of a document as an
object of type hw_api_content. The
parameter array contains the required elements
'objectidentifier' and the optional element 'mode'. The mode
can be one of the constants HW_API_CONTENT_ALLLINKS,
HW_API_CONTENT_REACHABLELINKS or HW_API_CONTENT_PLAIN.
HW_API_CONTENT_ALLLINKS means to insert all anchors even if
the destination is not reachable.
HW_API_CONTENT_REACHABLELINKS tells
hw_api_content() to insert only reachable links and
HW_API_CONTENT_PLAIN will lead to document without any
links.