It's not quite auto-mark but if you use the "Forum Tools" drop down menu, there is a selection titled "Mark Forum Read" that does exactly what it says.
There is also a "Quick Links" feature that marks all forums read.
Not automatic by any means but the functions are there.
Cranky Kong, Certified Rocket Monkey
"We were promised jet packs!"
Total Impulse in 2016: 1,318.99 Ns (Equivalent to a 3% K motor)
Total Impulse since 2010: 12,338.57 Ns (Equivalent to a 20% N motor)