Move 'string' module and fix 'typeOf' function

smnp/module/string/__init__.py

@@ -0,0 +1,4 @@
+from smnp.module.string.function import concat
+
+functions = [ concat.function ]
+methods = []

smnp/module/string/function/concat.py

@@ -0,0 +1,10 @@
+from smnp.library.model import Function
+from smnp.library.signature import varargSignature, ofType
+from smnp.type.model import Type
+
+_signature = varargSignature(ofType(Type.STRING))
+def _function(env, vararg):
+    return Type.string("".join([ arg.value for arg in vararg ]))
+
+
+function = Function(_signature, _function, 'concat')