message: Remove using std::string
diff: #define STB_DXT_IMPLEMENTATION
  #include <stb_dxt.h>
  -using namespace image;
  -
  -using std::string;
  -
  namespace image {
  static LinearImage extendToFourChannels(LinearImage source);
  @@ -316,15 +312,15 @@ CompressedTexture astcCompress(const LinearImage& original, AstcConfig config) {
  };
  }
  -AstcConfig astcParseOptionString(const string& configString) {
  +AstcConfig astcParseOptionString(const std::string& configString) {
  const size_t _1 = configString.find('_');
  const size_t _2 = configString.find('_', _1 + 1);
  - if (_1 == string::npos || _2 == string::npos) {
  + if (_1 == std::string::npos || _2 == std::string::npos) {
  return {};
  }
  - string quality = configString.substr(0, _1);
  - string semantic = configString.substr(_1 + 1, _2 - _1 - 1);
  - string blocksize = configString.substr(_2 + 1);
  + std::string quality = configString.substr(0, _1);
  + std::string semantic = configString.substr(_1 + 1, _2 - _1 - 1);
  + std::string blocksize = configString.substr(_2 + 1);
  AstcConfig config;
  if (quality == "veryfast") {
  config.quality = AstcPreset::VERYFAST;
  @@ -350,7 +346,7 @@ AstcConfig astcParseOptionString(const string& configString) {
  }
  const size_t _x = blocksize.find('x');
  - if (_x == string::npos) {
  + if (_x == std::string::npos) {
  return {};
  }
  config.blocksize[0] = std::stoi(blocksize.substr(0, _x));
  @@ -515,7 +511,7 @@ EtcConfig etcParseOptionString(const std::string& options) {
  return result;
  }
  -bool parseOptionString(const string& options, CompressionConfig* config) {
  +bool parseOptionString(const std::string& options, CompressionConfig* config) {
  config->type = CompressionConfig::INVALID;
  if (options.substr(0, 5) == "astc_") {
  config->astc = astcParseOptionString(options.substr(5));
  