Sfxr logo, custom waveforms

As discussed on the mailing list, I'm adding some custom waveform files to be used with triple osc, bitinvader, lfo's, etc.

Also a slight change to open the waveform directory by default when selecting user-defined waveform, instead of the default sample directory.

edit - Also: a fix on the LFO controller custom waveforms not getting saved/loaded with the project.