LDC 1.19.0-beta2

[kinke]

Glad to announce the second beta for LDC 1.19.

It's based on yesterday's DMD stable.
The bundled MinGW-based libs of prebuilt Windows packages have 
been upgraded to MinGW-w64 v7.0.0, with significant import 
library additions and changes. So if you target Windows and don't 
use the Microsoft toolchain, please participate in testing to 
prevent regressions for the final 1.19 release.

Full release log and downloads: 
https://github.com/ldc-developers/ldc/releases/tag/v1.19.0-beta2

Please help test, and thanks to all contributors!