Scroll offset should be reset by Memory Preset instruction

[hcs64]

ctx.hOffset and ctx.vOffset should be set to 0 by the CDG_MEMORY_PRESET instruction.

I hadn't encountered a disc with this issue until Tenchi Muyo! Ryo-ohki Hihoukan. Disc 5 (PICA-106005) is CD-G, and in a few places there's a scroll that finishes with non-zero offset and it doesn't get reset with another scroll command. By resetting with Memory Preset the next scene looks correct.

[bhj]

Thanks! Should be included in upcoming v7