Implement lazy loading in icelast.lua, fix doc

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

share/lua/sd/README.txt

@@ -27,12 +27,12 @@ VLC Lua SD modules should define two functions:
 
 
 User defined modules stored in the share/lua/modules/ directory are
-available. Read the 'Two pass Initialization section'
+available. Read the 'Lazy initialization' section
 
 Available VLC specific Lua modules: input, msg, net, object, sd,
 strings, variables, stream, gettext, xml. See lua/README.txt.
 
-## Two pass Initialization
+## Lazy Initialization
 
 SD Lua scripts are actually ran in two different contexts/interpreters. One of
 them is the one that will call your main() and search() functions. The other one
@@ -51,8 +51,9 @@ lazily_loaded = false
 dkjson        = nil
 
 function lazy_load()
-  if lazily_loaded ~= false then return nil end
+  if lazily_loaded then return nil end
   dkjson = require("dkjson")
+  lazily_loaded = true
 end
 
 function descriptor()

share/lua/sd/icecast.lua

@@ -19,7 +19,14 @@
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 --]]
-require "simplexml"
+
+lazily_loaded = false
+
+function lazy_load()
+    if lazily_loaded then return nil end
+    require "simplexml"
+    lazily_loaded = true
+end
 
 function descriptor()
     return { title="Icecast Radio Directory" }
@@ -30,6 +37,7 @@ function dropnil(s)
 end
 
 function main()
+    lazy_load()
     local tree = simplexml.parse_url("http://dir.xiph.org/yp.xml")
     for _, station in ipairs( tree.children ) do
         simplexml.add_name_maps( station )