Option to download sources in the launcher

The download speed of github is so terrible in China that it’s difficult to make a git clone to fetch the full source.
I would be be better if there is an option to include full sources when installing Flax via the launcher ( InstallFlax.exe), just like what UE4 does. Thanks.

Relevant discussion on Github: https://github.com/FlaxEngine/FlaxEngine/issues/387