Update vswhere version in install script.

Fix existing VS2022 detection.

Improve install script installation handling.

install_script: Improve vswhere detection.

Update install script to match recent changes in VSNASM.

Supports vswhere, multiple installation detection and VS2019 support.

closes #3  #2

Fix some typos in the readme.

Add git attributes.

Update instal script to delete any existing files.