Split CoreType DOUBLE into FLOAT32 and FLOAT64
Split CoreType DOUBLE into FLOAT32 and FLOAT64

This is slightly closer to WASM semantics.

Signed-off-by: Robert Young <42c59959a3f4413d6a1b4d7b4f99db457d199e49@gmail.com>

jduimovich/Base9,youngar/Base9,youngar/Base9,jduimovich/Base9,youngar/Base9