Preserve explicitly shaped empty state-space matrices so linearized interconnections with zero inputs and nonzero outputs keep a (noutputs, 0) D matrix.

Co-authored-by: OpenAI Codex <codex@openai.com>

Preserve automatic near-axis indentation when no direction is passed, but let explicit left/right override pole-side selection for poles within the indent radius.

Fixes python-control#1194

…interconnect-dmatrix

Fix zero-input interconnect D matrix shape

…ent-direction

Honor explicit Nyquist indent direction near imaginary axis

Squash-merge of python-control#1216

Fixes python-control#1204