Mangrove roots don't conduct redstone signals

The mangrove roots cannot conduct redstone signals, which the Java version currently does, causing a parity issue.

Steps to Reproduce:

1. Place one redstone repeater facing into some mangrove roots, and one repeater facing away from it
2. Power the first repeater

Observed Results:
The second repeater does not become powered.

Expected Results:
The second repeater should become powered.