DX7 envelope misbehavior

[dpwe]

eg0_type=amy.ENVELOPE_DX7 has difficulty with envelopes that exceed 1.0. So bp0='0,0,1000,2,0,0' appears to snap back to 1.0 when it hits sustain.

[dpwe]

After a quick look at the code, I think the problem is that:

• DX7 attack segments clip the end-point to max of 1 (the MIN(12.375, ...) in LINEAR_SAMP_TO_DX7_LEVEL
• Sustain segment doesn't look at eg_type and just returns the unclipped end-point.

I'm not sure what the right fix is here - either to allow DX7 envelopes to have targets beyond 1.0, or to modify sustain in DX7 to apply the same clipping. I would prefer to avoid the clip, but I've forgotten the details of the nonlinear MAP_ATTACK_LEVEL_S so I'm nervous to start modifying it.

[dpwe]

To my surprise, simply removing the MIN(12.375, ...) fixed the problem without apparently introducing any others.