Fix various sample downloader issues especially server redirect handling

Thanks to Mike W9MDB for the concept  of forcing to HTTP if OpenSSL is
not installed or if the user requires it for other reasons.

The sample  downloader should  now be usable  with or  without OpenSSL
libraries being  installed, so long  as SourceForge continue  to serve
identical  content from  both HTTP  and  HTTPS schemes  on their  file
servers and mirrors.

For users with baulked  OpenSSL installations, incorrect or incomplete
CA  certificate  stores,  either  the improved  capability  to  ignore
SSL/TLS errors for  the duration of a session at  their discretion or,
as a last resort a new option to force an HTTP URL scheme is provided.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7379 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

SampleDownloader/FileNode.cpp

@@ -11,9 +11,10 @@
 FileNode::FileNode (QTreeWidgetItem * parent
                     , QNetworkAccessManager * network_manager
                     , QString const& local_file_path
-                    , QUrl const& url)
+                    , QUrl const& url
+                    , bool http_only)
   : QTreeWidgetItem {parent, Type}
-  , remote_file_ {this, network_manager, local_file_path}
+  , remote_file_ {this, network_manager, local_file_path, http_only}
   , block_sync_ {false}
 {
   sync_blocker b {this};