xspect3d 1.06 released

Building on the solid foundation of xspect3d 1.05, 1.06 has a few new features and bug fixes.

New features are Dolph-Chebyshev data tapering windows, and a new bigger better main window. There are now 1024 frequency bins, instead of the old 512. Say goodbye to that pesky leakage with Blackman windows, and enjoy the Big Picture.

Another new feature is more accurate windowing power loss compensation. The power loss is restored after the FFT now, instead of before, which was quicker but not as accurate.

Removed FFTW wisdom files, as they don't really provide any speed-up.

Fixed an outstanding bug where if the graticule was showing in freeze mode, the toggle_3d_right function failed to redo the graticule, before showing the new graph.