v1.14.0

• New adjoint solver for density-based topology optimization, including
  filtering, automatic differentiation, and other frequencies (#1167).

• DFT functions now allow you to pass an arbitrary array of frequencies, instead
  of being limited to equally spaced frequencies (#1154 and #1156).

• Experimental shift-and-invert frequency-domain eigensolver (#1158).

• Renamed omega parameter to frequency at some places in the Python API,
  for consistency (#1171), and dft_fields object now takes fcen and df instead
  of freq_min and freq_max in Python.

• Support for SWIG 4.0 (#1159), and various other minor fixes.