New blocks for snapshot

Granite, Diorite, Andesite (new data values for blockid:1)
Iron trapdoor

See #1062
New snapshot block: slime blocks

See #1062
Merge branch 'master' into snapshot
Merge branch 'master' into snapshot
add new 14w25a prismarine and sea lantern blocks
Merge pull request #1119 from dbergl/prismarine

add new 14w25a prismarine and sea lantern blocks
Merge branch 'master' into snapshot
Merge remote-tracking branch 'origin/snapshot' into snapshot
Added support for the difference fence colors
added support for different door types
bump version to 1.8-pre3
Fix a typo and silly crash case

Would crash instead of gracefully exiting if a tileset dir wasn't provided. Might also change how the memory limit option works - currently has to be provided, even though that's not mentioned.
Merge pull request #1146 from computertechie/patch-1

Fix a typo and silly crash case
Merge branch 'snapshot'
Bump versions and docs for 1.8 support!
Forgot to bump version for travis
Added definitions and support for all the various red sandstone blocks.
Forgot texture file extensions in a couple places.
Lighting fixes for red sandstone stairs and slabs

Closes #1150
Closes #1149
Merge branch 'master' of git://github.com/overviewer/Minecraft-Overviewer