app: add LibreVNA logo and use it as icon launcher

Now it's possible to identify LibreVNA with a logo. This logo would be
visible as an icon when app is launched.

A banner containing same logo has been added to README. Also,
a desktop launcher file is created to be used in GNU/Linux environments
enabling in this way the ability to add as favorite.

Closes #57

README.md

@@ -1,4 +1,5 @@
-# LibreVNA
+![LibreVNA](Software/PC_Application/resources/banner.png)
+
 **100kHz to 6GHz VNA**
 
 This is the improved version of my [first attempt](https://www.github.com/jankae/VNA) at a VNA.

Software/PC_Application/LibreVNA-GUI.pro

@@ -298,7 +298,8 @@ FORMS += \
 DISTFILES +=
 
 RESOURCES += \
-    icons.qrc
+    icons.qrc \
+    resources/librevna.qrc
 
 CONFIG += c++17
 REVISION = $$system(git rev-parse HEAD)

Software/PC_Application/appwindow.cpp

@@ -78,6 +78,8 @@ AppWindow::AppWindow(QWidget *parent)
 //    qDebug().setVerbosity(0);
     qDebug() << "Application start";
 
+    this->setWindowIcon(QIcon(":/app/logo.png"));
+
     parser.setApplicationDescription(qlibrevnaApp->applicationName());
     parser.addHelpOption();
     parser.addVersionOption();

Software/PC_Application/resources/librevna.desktop

@@ -0,0 +1,9 @@
+[Desktop Entry]
+Name=LibreVNA GUI
+Comment=Vector Network Analyzer for LibreVNA board
+Exec=/opt/LibreVNA-GUI
+Terminal=false
+Type=Application
+StartupNotify=true
+Categories=Science;Engineering;Electronics
+Icon=librevna.png

Software/PC_Application/resources/librevna.qrc

@@ -0,0 +1,5 @@
+<RCC>
+	<qresource prefix="/app">
+	 	<file alias="logo.png">librevna.png</file>
+	</qresource>
+</RCC>