Move some functions to standard library

smnp/module/string/__init__.py

@@ -1,4 +1,4 @@
-from smnp.module.string.function import concat
+from smnp.module.string.function import concat, stringify
 
 functions = [ concat.function ]
-methods = []
+methods = [ stringify.function ]

smnp/module/string/function/stringify.py

@@ -0,0 +1,10 @@
+from smnp.function.model import Function
+from smnp.function.signature import signature
+from smnp.type.model import Type
+from smnp.type.signature.matcher.type import allTypes
+
+_signature = signature(allTypes())
+def _function(env, object):
+    return Type.string(object.stringify())
+
+function = Function(_signature, _function, 'toString')