Add script to generate AppImage

Issue #707.

.gitignore

@@ -8,3 +8,5 @@ qrc_*
 ui_*
 .DS_Store
 Info.plist
+*.AppImage
+AppDir/

appimage.sh

@@ -0,0 +1,97 @@
+#!/bin/bash
+
+# Simple recipe to generate an appimage for this app
+#
+# Options:
+#   * -u will upload your AppImage file after success to github under 
+#      "continous builds"  
+#
+# Requirements:
+#   * VERSION as an ENV var, if not detected will use actual github
+#     version + commit info
+#   * This must be run after a successfuly build, and need to set the
+#     APP var below to the path of the executable (default is the current
+#     travis build place: build/src/gqrx)
+#   * Must be run on a Linux version as old as the far distro you need to
+#     support, tested successfuly on Ubuntu 14.04 Trusty Tar
+#   * If you plan to use the "-u" option you need to configure some things
+#     for it to work, check this https://github.com/probonopd/uploadtool#usage
+#
+# On any troubles invoke stdevPavelmc in github 
+
+# Tweak this please: this is the path of the gqrx executable relative to
+#the project root will reside after build
+APP="build/src/gqrx"
+
+# No need to tweak below unles you move files on the actual project
+DESKTOP="gqrx.desktop"
+ICON="resources/icons/gqrx.svg"
+
+# clean log space
+echo "==================================================================="
+echo "                Starting to build the AppImage..."
+echo "==================================================================="
+echo ""
+
+# Detect the version or craft one from the actual github status and commit
+if [ -z "$VERSION" ] ; then
+    # build the version string
+    echo "Ops! VERSION not set, crafting a version from github data..."
+    echo ""
+    export VERSION=`git describe --abbrev=8`
+fi
+
+# version notice
+echo "You are building Gqrx version: $VERSION"
+echo ""
+
+# basic tests
+if [ ! -f "$APP" ] ; then
+    echo "Error: the app file is no in the path we need it, update the APP var on this script"
+    exit 1
+fi
+
+if [ ! -f "$DESKTOP" ] ; then
+    echo "Error: can't find the desktop file, please update the DESKTOP var on the scriot"
+    exit 1
+fi
+
+if [ ! -f "$ICON" ] ; then
+    echo "Error: can't find the default icon, please update the ICON var in the script"
+    exit 1
+fi
+
+# prepare the ground
+rm -rdf AppDir 2>/dev/null
+rm -rdf Gqrx-*.AppImage 2>/dev/null
+
+# download & set all needed tools
+wget -c -nv "https://github.com/linuxdeploy/linuxdeploy/releases/download/continuous/linuxdeploy-x86_64.AppImage"
+wget -c -nv "https://github.com/linuxdeploy/linuxdeploy-plugin-qt/releases/download/continuous/linuxdeploy-plugin-qt-x86_64.AppImage"
+wget -c -nv "https://github.com/linuxdeploy/linuxdeploy-plugin-appimage/releases/download/continuous/linuxdeploy-plugin-appimage-x86_64.AppImage"
+chmod a+x *.AppImage
+
+# abra-cadabra
+./linuxdeploy-x86_64.AppImage -e "$APP" -d "$DESKTOP" -i "$ICON" -p qt --output appimage --appdir=./AppDir
+RESULT=$?
+
+# check build success
+if [ $RESULT -ne 0 ] ; then
+    # warning something gone wrong
+    echo ""
+    echo "ERROR: Aborting as something gone wrong, please check the logs"
+    exit 1
+else
+    # success
+    echo ""
+    echo "Success build, check your file:"
+    ls -lh Gqrx-*.AppImage
+fi
+
+if [ "$1" == "-u" ] ; then
+    # must upload to continous releases
+    # see https://github.com/probonopd/uploadtool#usage for configs to be done
+    # for this to work as needed
+    wget -c https://github.com/probonopd/uploadtool/raw/master/upload.sh
+    bash upload.sh Gqrx-*.AppImage
+fi