* Fix chart background based on theme

* Change chart history to one day based on some devices having less history.(thanks michael.hufer@gmx.de)
* Have charts min/max be based on actual data received instead of hard coded values.(thanks michael.hufer@gmx.de)

src/miflora/miflora.h

@@ -96,7 +96,8 @@ private:
     const QByteArray magicBytes = QByteArray::fromHex("a01f");
     const QByteArray historyReadInit = QByteArray::fromHex("a00000");
     
-
+    const quint16 historySize = 24;
+    
     float temp = 0.0;
     quint32 bright = 0;
     quint8 moisture = 0;