This function loads the posts in a topic up so they can be displayed.

• Supports wireless, using wap/wap2/imode and the Wireless templates.
• Uses the main sub template of the Display template.
• Requires a topic, and can go to the previous or next topic from it.
• Jumps to the correct post depending on a number/time/IS_MSG passed.
• Depends on the defaultMaxMessages and enableAllMessages settings.
• Is accessed by ?topic=ID_TOPIC.START.