Generate and upload AppImage

[probonopd]

This PR, when merged, will compile this application on Travis CI upon each git push, and upload an AppImage to your GitHub Releases page.

Providing an AppImage would have, among others, these advantages:

• Applications packaged as an AppImage can run on many distributions (including Ubuntu, Fedora, openSUSE, CentOS, elementaryOS, Linux Mint, and others)
• One app = one file = super simple for users: just download one AppImage file, make it executable, and run
• No unpacking or installation necessary
• No root needed
• No system libraries changed
• Works out of the box, no installation of runtimes needed
• Optional desktop integration with appimaged
• Optional binary delta updates, e.g., for continuous builds (only download the binary diff) using AppImageUpdate
• Can optionally GPG2-sign your AppImages (inside the file)
• Works on Live ISOs
• Can use the same AppImages when dual-booting multiple distributions
• Can be listed in the AppImageHub central directory of available AppImages
• Can double as a self-extracting compressed archive with the --appimage-extract parameter
• No repositories needed. Suitable/optimized for air-gapped (offline) machines
• Decentralized

Here is an overview of projects that are already distributing upstream-provided, official AppImages.

PLEASE NOTE: For this to work, you need to set up GITHUB_TOKEN in Travis CI for this to work; please see https://github.com/probonopd/uploadtool.

If you have questions, AppImage developers are on #AppImage on irc.freenode.net.

[probonopd]

An AppImage for testing can be downloaded at
https://github.com/probonopd/mumble/releases/tag/continuous

[probonopd]

How can we make this show the git commit hash instead of "Compiled by User"?

[probonopd]

I think the macOS build failure is unrelated to my changes.

[davidebeatrici]

Thank you very much for your contribution!

How can we make this show the git commit hash instead of "Compiled by User"?

mumble/src/Version.h

Lines 9 to 16 in 41502bb

	#define MUMXTEXT(X) #X
	#define MUMTEXT(X) MUMXTEXT(X)
	#ifndef MUMBLE_VERSION
	#define MUMBLE_RELEASE "Compiled by User"
	#else
	#define MUMBLE_RELEASE MUMTEXT(MUMBLE_VERSION)
	#endif

We can get the commit hash from the TRAVIS_COMMIT environment variable.

qmake CONFIG+="release tests g15-emulator ${EXTRA_CONFIG}" DEFINES+="MUMBLE_VERSION=$TRAVIS_COMMIT" -recursive && make -j2 && make check

I think the macOS build failure is unrelated to my changes.

Indeed, we didn't fix it yet because multiple changes are required due to deprecated stuff (e.g. the i386 architecture).

[probonopd]

Thanks @davidebeatrici much better but a bit long

Hence I am going for DEFINES+="MUMBLE_VERSION=${TRAVIS_COMMIT:0:7}" now.

[davidebeatrici]

Sounds good.

[probonopd]

I think it is looking good now:

[davidebeatrici]

Thank you again!