Add catches_strings test to test throws char * typemap

Examples/test-suite/lua/catches_strings_runme.lua

@@ -0,0 +1,10 @@
+require("import")	-- the import fn
+import("catches_strings")	-- import code
+
+-- catch "undefined" global variables
+local env = _ENV -- Lua 5.2
+if not env then env = getfenv () end -- Lua 5.1
+setmetatable(env, {__index=function (t,i) error("undefined global variable `"..i.."'",2) end})
+
+s, msg = pcall(function() catches_strings.StringsThrower.charstring() end)
+assert(s == false and msg:find("charstring message", 1, true))