Cutting-edge prebuilt CI packages for Linux/OSX/Windows

[kinke]

Hi all,

LDC now features automatically deployed prebuilt binaries for 
Linux/OSX x86_64 too (built after each push to the master 
branch). Download them from the GitHub CI release:

https://github.com/ldc-developers/ldc/releases/tag/CI

The packages are equivalent to the release packages except for 
enabled LLVM and LDC assertions, so expect a slower compilation 
speed.