fix prismarine stairs

Sorry for the noise in mc_id.h, but somebody decided they want DOS
line endings and I couldn't allow that to happen. When not doing that
put the whole thing into diff, I decided to just fix the indentation
too while I was at it.

Needed bugfixing of some overlooked unsigned char usages for block IDs,
as otherwise the lighting would be scuffed.

Concerns issue #1486.

overviewer_core/world.py

@@ -772,6 +772,8 @@ class RegionSet(object):
             'minecraft:acacia_trapdoor': (11335, 0),
             'minecraft:dark_oak_trapdoor': (11336, 0),
             'minecraft:petrified_oak_slab': (126, 0),
+            'minecraft:prismarine_stairs': (11337, 0),
+            'minecraft:dark_prismarine_stairs': (11338, 0),
         }
 
         colors = [   'white', 'orange', 'magenta', 'light_blue',