Revert "Do not force anyone to use -Wdouble-promotion"

This reverts commit a639dda521e09cb73a6711fd5e67a78a5e8dfe03.
Revert "IOPs are now compliant with -Wdouble-promotion"

This reverts commit f51a497795ea3856c20b68c0d24f5cc230db7e37.