More intuitive handling of calibration measurements

- Allow saving of calibration only if a calibration is active (no more
calibration files that "don't do anything" when they are opened)
- Delete old measurements when loading a new calibration file
- Update calibration when a measurement is updated (no need to disable
and enable again)
- Disable calibration when a required measurement is deleted

Software/PC_Application/CustomWidgets/informationbox.cpp

@@ -0,0 +1,43 @@
+#include "informationbox.h"
+#include <QCheckBox>
+#include <QSettings>
+#include <QDebug>
+
+void InformationBox::ShowMessage(QString title, QString message, QWidget *parent)
+{
+    // check if the user still wants to see this message
+    auto hash = qHash(message);
+
+    QSettings s;
+    if(!s.contains(hashToSettingsKey(hash))) {
+        auto box = new InformationBox(title, message, hash, parent);
+        box->exec();
+    }
+}
+
+InformationBox::InformationBox(QString title, QString message, unsigned int hash, QWidget *parent)
+    : QMessageBox(parent),
+      hash(hash)
+{
+    setWindowTitle(title);
+    setText(message);
+    setAttribute(Qt::WA_DeleteOnClose, true);
+    setIcon(QMessageBox::Information);
+
+    auto cb = new QCheckBox("Do not show this message again");
+    setCheckBox(cb);
+}
+
+InformationBox::~InformationBox()
+{
+    auto cb = checkBox();
+    if(cb->isChecked()) {
+        QSettings s;
+        s.setValue(hashToSettingsKey(hash), true);
+    }
+}
+
+QString InformationBox::hashToSettingsKey(unsigned int hash)
+{
+    return QString("DoNotShowDialog/") + QString::number(hash);
+}