Lua Fix utf8encode, remove utf16 functions

The auto generated utf8/16 encode/decode functions did not work.
Upon implementing them correctly I found that lua handles the utf-8
form properly but I could not get utf-16 to work without crashing
maybe someone can come along later and implement utf-16 safe string
functions but for now utf-16 is removed.

Change-Id: I97a044e200dc27f683a45487cd93fce667c670c4

apps/plugins/lua/rocklib_aux.pl

@@ -70,6 +70,9 @@ my @forbidden_functions = ('^open$',
                            '^s?+rand$',
                            '^strl?+cpy$',
                            '^strl?+cat$',
+                           '^iso_decode$',
+                           '^utf8encode$',
+                           '^utf16',
                            '^codec_',
                            '^timer_',
                            '^lcd_(mono_)?+bitmap',