MSYS2 Installer 20161025.0.0

This lightweight package performs an unattended installation of MSYS2 using official installer. It is intended as an alternative to msys2 and msys2.install packages which might be a better choice for some users.

Major differences when compared to [MSYS2](https://chocolatey.org/packages/msys2) package:
 - Installation is performed from official `.exe` binaries instead of `.tar.xz` archives
 - Unattended installation only without any additional customization or configuration (not even `pacman --noconfirm -Syuu`)

Major differences when compared to [msys2.install](https://chocolatey.org/packages/msys2.install) package:
 - `msys2.install` package is currently broken and not yet approved
 - Support for unattended uninstall
 - QtInstaller window is visible so that user can track progress and optionally answer MessageBox that is hard to automate (e.g. Corrupt_Installation_Error)