GENERAL: Build and deploy binaries for mac osx

[gurcei]

It'd be nice if our Jenkins builds could also cross-compile for Mac OSX too, as we could then get some early feedback on whether any commits break builds for mac osx.

A quick google found this SO thread which had a few suggestions which could be considered:

• https://stackoverflow.com/questions/693952/how-to-compile-for-os-x-in-linux-or-windows

[gurcei]

I'm taking a look at Gabor's .travis.yml used in xemu, and will try follow suit:

• https://github.com/lgblgblgb/xemu/blob/master/.travis.yml

[gurcei]

Ok, the .travis.yml file has been updated to build and deploy the following files into the github's 'CI-latest' release:

• RELEASE-OSX.txt (info on which osx files were uploaded, and some date/version info, to help assure you they are 'new')
• mega65_ftp.osx
• m65.osx
• bit2core.osx

Tayger has tested these binaries on his mac (osx Catalina), working fine.

I suspect that some mac users might run into problems with different versions of dynamic libraries, but I'll save the idea of switching to statically linked libraries for another future ticket, if we hear back from mac people with such problems.