Texts are not only kept inside original layers, but
also inside deep layers. This enables using texts
from DRC.
However, texts in deep layers are kept as markers.
Mostly they are converted back to texts, but the
orientation will be lost.
The change eliminates the need to using Iterators
in DRC instead of original layers and use of
label layers in deep mode.
A drawback is the presence of marker shapes in
deep mode (unless polygon layers are created).
Also, text output to RDB is not supported from
deep layers currently.