Updated install Emscripten script

The new version of Emscripten has changed the path bat file name.
Added clear context option

Added the ability to disable the clearing of the context.
Tab to spaces

Converted tabs to spaces.
Fixed issue with tabs

I had converted  every tab to spaces. Pulled existing file and added
change.
Revert "Updated install Emscripten script"

This reverts commit d95941cacb6199457faecee3eea125f3c7fcac99.