fix hidden check to use also alpha value
Fix documentation bug
Merge pull request #522 from justinseanmartin/jmartin/fix-documentation-bug

Fix documentation bug
Merge pull request #516 from ivan-golub/advanced_hidden_check

Extend hidden check to use also alpha value
Remote osx_image (experimental and may be removed)

https://github.com/travis-ci/travis-yaml/blob/0f2cc8c2887790d2980f4f0af81912afcc030226/SPEC.md#osx_image
Parallelize build over iOS SDKs