Refactor, test and improve the way we cut too-long messages for IRC

louloulibs/utils/string.cpp

@@ -4,3 +4,15 @@ bool to_bool(const std::string& val)
 {
   return (val == "1" || val == "true");
 }
+
+std::vector<std::string> cut(const std::string& val, const std::size_t size)
+{
+  std::vector<std::string> res;
+  std::string::size_type pos = 0;
+  while (pos < val.size())
+    {
+      res.emplace_back(val.substr(pos, size));
+      pos += size;
+    }
+  return res;
+}