Fix overlay_wpipe issues

[mrecachinas]

This fixes:

• a small typo in naming within onmessage: event vs evt
• an issue with layer 1D: overrides.pipe = true should be set even for 1D

This replaces some console.log statements with m.log.debug.

This begins to remove dfmap and wpipe.arrayFormat in favor of simply using hcb.createArray.