Shift+Ctrl+X for advanced users that likes to customize the image

- Adds "hidden" shift+ctrl+X shortcut for eXpert image customization
  options.

Allows one to set certain options on RPI OS images, namely:

* disable overscan
* set hostname
* enable ssh and
  - set Pi user password if using password authentication
  OR
  - set authorized_keys
    (if running Imager on Linux/Mac this will
     have contents of ~/.ssh/id_rsa.pub prefilled)
* configure wifi settings
  (if computer running Imager is connected by wifi it will
  prefill wifi SSID and if on Windows also PSK).
* set time zone and keyboard layout

  Related to feature requests/issues:
  Ref #127
  Ref #86
  Ref #102
  Ref #73
  Ref #68
  Ref #25
  Ref #12

- Option Window also allows setting a couple other general settings:

* Adds option for audible notification (beep) when imaging completes.
  Closes #46

* Adds option not to eject media when done.
  Closes #144

- No longer suspends a number of Windows services during Imaging
  (We want Windows to detect the drive and mount it, or we may
   not be able to alter files on FAT partition).

imagewriter.h

@@ -92,6 +92,20 @@ public:
     /* Returns a json formatted list of the OS images found on USB stick */
     Q_INVOKABLE QByteArray getUsbSourceOSlist();
 
+    /* Functions to collect information from computer running imager to make image customization easier */
+    Q_INVOKABLE QString getDefaultPubKey();
+    Q_INVOKABLE QString getTimezone();
+    Q_INVOKABLE QStringList getTimezoneList();
+    Q_INVOKABLE QStringList getCountryList();
+    Q_INVOKABLE QString getSSID();
+    Q_INVOKABLE QString getPSK(const QString &ssid);
+
+    Q_INVOKABLE bool getBoolSetting(const QString &key);
+    Q_INVOKABLE void setSetting(const QString &key, const QVariant &value);
+    Q_INVOKABLE void setImageCustomization(const QByteArray &config, const QByteArray &cmdline, const QByteArray &firstrun);
+
+    Q_INVOKABLE QString crypt(const QByteArray &password);
+
 signals:
     /* We are emiting signals with QVariant as parameters because QML likes it that way */
 
@@ -124,7 +138,7 @@ protected slots:
 protected:
     QUrl _src, _repo;
     QString _dst, _cacheFileName, _parentCategory, _osName;
-    QByteArray _expectedHash, _cachedFileHash;
+    QByteArray _expectedHash, _cachedFileHash, _cmdline, _config, _firstrun;
     quint64 _downloadLen, _extrLen, _devLen, _dlnow, _verifynow;
     DriveListModel _drivelist;
     QQmlApplicationEngine *_engine;