Integrate with travis-ci

[gamedevsam]

Travis provides continuous build support (including pull requests). This would let us know if a pull request would cause a compiler error.

https://travis-ci.org/

[caitp]

+1for CI

[reduz]

I'm not quite sure I understand what travis-ci is, I kind of understand that it's a platform for continuous integration, but I'm not sure which tagrets can compile. Right now I'm using jenkins at my office server to make the builds at night, and having it configured so it does builds for android, html5 bb10, etc is quite a lot of work. Maybe it could be used for the 32 bits linux binary :P

[gamedevsam]

Travis uses virtualized linux boxes to do the integrations, so I think compiling the 32 bit linux binary is about as far as we could get. I still think that would be useful though.

[caitp]

I recall they were adding VMs for other platforms in the soon-ish future, although these are probably not available free of charge. But open source projects can take advantage of linux containers at no cost, so that's nice.

An alternative solution could be Jenkins CI alongside Leeroy for github integration, which would allow more flexibility in the target systems

[bdero]

@reduz I was about to suggest the use of Travis for per-commit builds, but if you're using Jenkins, that's great, too.

An uprising practice is to run full build and test suite jobs against every commit on every pull request for automated integration into the code review process.

Notice how edX does it: https://github.com/edx/edx-platform/pull/6609
Next to each commit, there's an icon indicating the build status:

Clicking it takes the user to the build report to pinpoint test/build failures:

Of course, building Godot for all platforms on every push might be intense on compute time. The bright side is that, since Godot has surprisingly few dependencies, build configuration is probably quite a bit simpler than it could be.

[erbridge]

Looks like Travis is already set up to do the Linux build. There's a .travis.yml file which looks like it's set up correctly to me. It only needs to be turned on.

[leonkrause]

The discussion about continuous integration is continued in #1553.