EclaireXL

Allow reading the record reg.

Fix the CPU writes to sample ram

Allow recording of a channel to the sample memory (for looping etc). Allow feeding a channel to the SID ext input, in order to use filters. This mutes the original channel so its not duplicated..

ADPCM decoding bug

Use natural signed/unsigned source depending on which chip. Mix with signed, with a dc blocker. Add a bit more dither to make the mid level voltage acceptable through the sigma delta, since it now sits a 2.5v for silence (internally, external is ac coupled). This fixes the sample engine clicks when playing mod files due to the sample engine volume being applied on unsigned converted samples, which gave a dc bias betwen samples. Paula samples have to end/start at signed midpoint you see.

Specified as RW in dev guide