Fix Settings & Interleave Audio Data

[kblaschke]

Fixed two issues leading to crashes:

• The projectm_settings struct was not properly initialized, e.g. the font filename pointers potentially contained random data
• Adding audio data did not work properly due to an incorrect pointer being passed, crashing the plug-in
• Audio data was passed in the wrong order [LLL][RRR], and is now interleaved to [LR][LR][LR] as projectM expects it.

[revmischa]

Suggested change

	for (auto sample = 0; sample < kVisualNumWaveformEntries; sample++)
	for (auto sample = 0; sample < kVisualNumWaveformEntries * kVisualMaxDataChannels; sample+= kVisualMaxDataChannels)

?

[kblaschke]

No, that would read & write twice the size of the source and destination arrays. kVisualMaxDataChannels is hard-coded to 2 in the header, so it'll never change unless we do it. That correct? Dunno, it works.