[ENH] Time frequency plugin

[juangpc]

still a lot of things to do.

initial time-frequency plugin *this includes a barebones random data plugin to be able to see functionality. Needs:

• this needs channel selection working.
• inclusion of fftw in the project.
• parallel filtering of each channel.
• selection of overlapping window, other characteristics. even tapering(?).
• showing image.
• cone of confidence.