message: Visual Studio 2017 compilation fix
diff: #include <list>
  #include <string>
  +#include <cctype>
  #include <cstring>
  void readDSNinfo(ConnInfo * ci, bool overwrite) {
  @@ -121,7 +122,7 @@ key_value_map_t readConnectionString(const std::string & connection_string) {
  const auto consume_space = [] (std::string & str) {
  std::size_t num = 0;
  - while (!str.empty() && std::isspace(str[num])) {
  + while (!str.empty() && std::isspace(static_cast<unsigned char>(str[num]))) {
  ++num;
  }
  str.erase(0, num);
  @@ -165,7 +166,7 @@ key_value_map_t readConnectionString(const std::string & connection_string) {
  }
  }
  - while (!key.empty() && std::isspace(key.back())) {
  + while (!key.empty() && std::isspace(static_cast<unsigned char>(key.back()))) {
  key.pop_back();
  }
  @@ -212,7 +213,7 @@ key_value_map_t readConnectionString(const std::string & connection_string) {
  throw std::runtime_error("'}' expected");
  }
  else {
  - while (!value.empty() && std::isspace(value.back())) {
  + while (!value.empty() && std::isspace(static_cast<unsigned char>(value.back()))) {
  value.pop_back();
  }
  }
  