Fix error uploading spectrum files with non-ISO-8859-1 code points in…

… the filename.

When the user drag-n-dropped a  file onto InterSpec, a JS exception would be thrown when setting the "X-File-Name" header, if the filename contained a non-ISO-8859-1 code point (ex. IPC_ӨФфФЙжѿ_1.n42).
Now URI encodes filename to put in the header, and URI-decodes in the C++.

js/InterSpec.js

@@ -101,8 +101,8 @@ function()
         xhr.setRequestHeader("Content-type", "application/x-spectrum");
         xhr.setRequestHeader("Cache-Control", "no-cache");
         xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
-        xhr.setRequestHeader("X-File-Name", file.name);
-
+        // Filename may have non-ISO-8859-1 code points, so we need to URI encode it
+        xhr.setRequestHeader("X-File-Name", encodeURIComponent(file.name));
 
 //#if( BUILD_AS_ELECTRON_APP ) //C++ preprocessors dont look to work here...
         if( lookForPath && (typeof file.path === "string") && (file.path.length > 2) && !file.path.toLowerCase().includes('fake') ) {

src/FileDragUploadResource.cpp

@@ -214,8 +214,10 @@ void FileDragUploadResource::handleRequest( const Http::Request& request,
     {
       spool_file << request.in().rdbuf();
       spool_file.close();
-      const string userName = request.headerValue( "X-File-Name" );
+      const string userNameEncoded = request.headerValue( "X-File-Name" );
+      const string userName = Wt::Utils::urlDecode(userNameEncoded);
 
+      cout << "userNameEncoded='" << userNameEncoded << "' --> userName='" << userName << "'" << endl;
       //cerr << "\n\n\nuserName = '" << userName << "'\n\n" << endl;
 
       auto app = WApplication::instance();