Merge branch 'signal_tunnels_bridges' into jgrpp

# Conflicts:
#	src/saveload/afterload.cpp
#	src/saveload/extended_ver_sl.cpp

docs/landscape.html

@@ -1620,7 +1620,7 @@
        <li>m6 bit 1: set = semaphore signals, clear = light signals</li>
        <li>m6 bit 0: set = entrance signal shows green, clear = entrance signal shows red</li>
        <li>m2 bit 15: for bridge entrances only: storage for visual red/green state of signals starting from 15 is allocated outside the map array</li>
-       <li>m2 bits 14..0: for bridge entrances only: for signals 0..14 on bridge, signal is visually red if corresponding bit in 0..14 is set</li>
+       <li>m2 bits 14..4: for bridge entrances only: for signals 0..10 on bridge, signal is visually red if corresponding bit in 4..14 is set</li>
       </ul>
      </li>
      <li>m5 bits 3..2: transport type