Ahkab v 0.18

Changelog for v 0.18

Version 0.18 represents the culmination of almost two months of efforts, yet
another step in the current time-based release scheme.

This release features support for the Fourier (.FOUR) and Fast Fourier Transform
directives (.FFT). Piece-wise linear functions are also now supported in Python,
with extra features like a repeat directory to enable periodicity.

Moreover, as in the previous releases, several commits were devoted to improving
the documentation: you can find the new, improved documentation online at
http://ahkab.readthedocs.org/en/latest/

Features added:

• Add .FOUR and .FFT support
• Add PWL waveforms (available from python only)

Backwards incompatible changes:

• AC analyses are from now defined in Hz (compliant with SPICE). This also means
  that there is no omega (accessed through 'w') in the results set, it is now
  replaced by a frequency vector, expressed in Hz and accessed as 'f'.

User code can be usually easily fixed substituting 2*pi*r[w] with r[f]
or the like. Sorry for any trouble this creates.

Changes from contributors and pull requests merged:

None.

Bugs fixed, short list:

BUGFIX: Fix opening of files in system that do not default to utf-8
BUGFIX: Suppress error message on Windows
BUGFIX: Use all assumptions, fix #32
BUGFIX: fix reading the netlist from stdin
BUGFIX: Use different options for SH and BFPSS
BUGFIX: no DC value -> return t=0
BUGFIX: convert to uppercase before comparison