Add-ons [tl] Thread Symbiotics 1.0.3

Description: Make more threads which link to an existing thread.
Symbiotic threads work like the current thread redirect but with few differences:

• Symbiotic threads is permanently redirects
• Symbiotic threads have last post info and display as normal threads in thread list.
• One existing thread can have more symbiotic
• Automatically update symbiotic thread stats when the source thread updated.