IPTV m3u channel import with USA channel numbers

Allow IPTV m3u channel importing from HDHomeRun tuners to insert
channels with decimals, such as "2.1" or "23.11"
The validation of HDHomeRun channel numbers is changed to allow
any non-empty string as channel number instead of only an integer number.

Refs #860

mythtv/libs/libmythtv/channelscan/iptvchannelfetcher.cpp

@@ -536,16 +536,15 @@ static bool parse_extinf(const QString &line,
 
     // Parse extension, HDHomeRun style
     // EG. #EXTINF:-1 channel-id="22" channel-number="22" tvg-name="Omroep Brabant",22 Omroep Brabant
+    //     #EXTINF:-1 channel-id="2.1" channel-number="2.1" tvg-name="CBS2-HD",2.1 CBS2-HD
     static const QRegularExpression chanNumName6
         { R"(^-?\d+\s+channel-id=\"([^\"]+)\"\s+channel-number=\"([^\"]+)\"\s+tvg-name=\"([^\"]+)\".*$)" };
     match = chanNumName6.match(line);
     if (match.hasMatch())
     {
         channum = match.captured(2).simplified();
         name = match.captured(3).simplified();
-        bool ok = false;
-        int channel_number = channum.toInt (&ok);
-        if (ok && (channel_number > 0))
+        if (!channum.isEmpty() && !name.isEmpty())
         {
             return true;
         }