Add option to anchor a preview window to a position.
Add option to anchor a preview window to a position.

joshwatson/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api