attempt is made to write an abstract view to GDS. This behavior can
be overridded with the new command option "gds abstract [enable|disable]".
Also: Corrected extraction to allow split tiles to be set as the
reference tile for a node. Previously this was allowed only if the
tile was the first to be searched, but that can cause different tiles to
be marked as the reference depending on where the search starts,
resulting in different names for the same node in .ext files, which is
bad. Also: Modified the LEF annotation to avoid bad entries in the LEF
that would create layers in the layout where none exist.
0dac37cb46