Creates an slob object and opens it. Modes: 1 = LO_RDONLY, 2 = LO_WRONLY, 4 = LO_APPEND, 8 = LO_RDWR, 16 = LO_BUFFER, 32 = LO_NOBUFFER -> or-mask. You can also use constants named IFX_LO_RDONLY, IFX_LO_WRONLY etc. Return FALSE on error otherwise the new slob object-id.