Common: Cleanup AssetReader extension filter.

Common/File/FileUtil.cpp

@@ -532,7 +532,7 @@ std::string GetFileExtension(const std::string & fn) {
 	if (pos == std::string::npos) {
 		return "";
 	}
-	std::string ext = fn.substr(pos + 1);
+	std::string ext = fn.substr(pos);
 	for (size_t i = 0; i < ext.size(); i++) {
 		ext[i] = tolower(ext[i]);
 	}

Common/File/PathBrowser.cpp

@@ -114,7 +114,7 @@ std::vector<File::FileInfo> ApplyFilter(std::vector<File::FileInfo> files, const
 	auto pred = [&](const File::FileInfo &info) {
 		if (info.isDirectory || !filter)
 			return false;
-		std::string ext = "." + File::GetFileExtension(info.fullName);
+		std::string ext = File::GetFileExtension(info.fullName);
 		return filters.find(ext) == filters.end();
 	};
 	files.erase(std::remove_if(files.begin(), files.end(), pred), files.end());

Common/File/VFS/AssetReader.cpp

@@ -74,7 +74,7 @@ bool ZipAssetReader::GetFileListing(const char *orig_path, std::vector<File::Fil
 	if (filter) {
 		while (*filter) {
 			if (*filter == ':') {
-				filters.insert(tmp);
+				filters.insert("." + tmp);
 				tmp = "";
 			} else {
 				tmp.push_back(*filter);
@@ -83,7 +83,7 @@ bool ZipAssetReader::GetFileListing(const char *orig_path, std::vector<File::Fil
 		}
 	}
 	if (tmp.size())
-		filters.insert(tmp);
+		filters.insert("." + tmp);
 
 	// We just loop through the whole ZIP file and deduce what files are in this directory, and what subdirectories there are.
 	std::set<std::string> files;

Core/Loaders.cpp

@@ -72,7 +72,7 @@ IdentifiedFileType Identify_File(FileLoader *fileLoader) {
 		return IdentifiedFileType::ERROR_IDENTIFYING;
 	}
 
-	std::string extension = "." + File::GetFileExtension(fileLoader->GetPath());
+	std::string extension = File::GetFileExtension(fileLoader->GetPath());
 	if (extension == ".iso") {
 		// may be a psx iso, they have 2352 byte sectors. You never know what some people try to open
 		if ((fileLoader->FileSize() % 2352) == 0) {