Warns if plugin class not instantiable

The class returned from NSClassFromString is checked and a warning is produced if it is nil.
Merge pull request #15 from NatWeiss/patch-1

Warns if plugin class not instantiable
add 64bit
fix redefine bugs
IOSIAP didn't fish remove it
Merge pull request #38 from wuzhiming/PluginXJSB

add 64bit support
Merge branch 'jsb_modify' of https://github.com/joshuastray/plugin-x into jsb_modify
Merge branch 'jsb_modify' of https://github.com/joshuastray/plugin-x into jsb_modify
Update bindings
Merge pull request #1 from pandamicro/jsb_modify

Update bindings