Remove df2mc plugin (obsolete)

It's still got it's own repo, but it hasn't been compatible with
Minecraft for years and shouldn't be in the DFHack repo.

.gitmodules

@@ -4,9 +4,6 @@
 [submodule "plugins/isoworld"]
 	path = plugins/isoworld
 	url = git://github.com/DFHack/isoworld.git
-[submodule "plugins/df2mc"]
-	path = plugins/df2mc
-	url = git://github.com/DFHack/DF2MC.git
 [submodule "library/xml"]
 	path = library/xml
 	url = git://github.com/DFHack/df-structures.git

plugins/CMakeLists.txt

@@ -24,12 +24,6 @@ if(BUILD_DEV_PLUGINS)
     add_subdirectory (devel)
 endif()
 
-#It's dead :<
-#OPTION(BUILD_DF2MC "Build DF2MC (needs a checkout first)." OFF)
-#if(BUILD_DF2MC)
-#    add_subdirectory (df2mc)
-#endif()
-
 OPTION(BUILD_MAPEXPORT "Build map exporter." ON)
 if (BUILD_MAPEXPORT)
 #    add_subdirectory (mapexport)

plugins/df2mc

@@ -1 +0,0 @@
-Subproject commit 5b167d2ba89b877d80e0609feae8771aeaef356d