[libcalamares] Implement GeoIP Handler config from map

- read map entries with alternate keys
 - delegate to other constructor

src/libcalamares/geoip/Handler.cpp

@@ -25,6 +25,7 @@
 
 #include "utils/Logger.h"
 #include "utils/NamedEnum.h"
+#include "utils/Variant.h"
 
 #include <QEventLoop>
 #include <QNetworkRequest>
@@ -73,6 +74,22 @@ Handler::Handler( const QString& implementation, const QString& url, const QStri
     }
 }
 
+static QString
+getMapAlternates( const QVariantMap& config, const QString& key1, const QString& key2 )
+{
+    QString r = CalamaresUtils::getString( config, key1 );
+    if ( r.isEmpty() )
+        r = CalamaresUtils::getString( config, key2 );
+    return r;
+}
+
+Handler::Handler( const QVariantMap& config )
+    : Handler( getMapAlternates( config, QStringLiteral( "style" ), QStringLiteral( "geoipStyle" ) ),
+               getMapAlternates( config, QStringLiteral( "url" ), QStringLiteral( "geoipUrl" ) ),
+               getMapAlternates( config, QStringLiteral( "selector" ), QStringLiteral( "geoipSelector" ) ) )
+{
+}
+
 Handler::~Handler()
 {
 }

src/libcalamares/geoip/Handler.h

@@ -64,9 +64,6 @@ public:
      *  - implementation from "style" or "geoipStyle" (if the first does not exist)
      *  - url from "url" or "geoipUrl" (if the first does not exist)
      *  - selector from "selector" or "geoipSelector" (if the first does not exist)
-     * Unlike the 3-QString Handler constructor, this also understands implementations
-     * "legacy" and blank, which are interpreted as "JSON", except that the url is extended
-     * by "/json/" before fetching.
      */
     Handler( const QVariantMap& config );