Reduce part layers

Problem environment

Two board layers are used for parts population, although it's unlikely more than one are needed.

Steps to reproduce

1. Observe parts on the bottom layer
2. Compare area needed with top layer space available

Expected result

The top layer has no available space.

Actual result

The top layer has enough empty space to accommodate the bottom parts.

Workaround Note

It's likely to be easier to reduce layer population after antenna and connector selection is final, because early designs include multiple redundant parts.

Severity level

This is medium priority because one layer population frees resources.

Resolved by recent modifications removing all parts from the bottom layer.