Merged back changes made in AudioKit

[megastep]

Hi there,

These are mostly some changes I've done while integrating the current version of EZAudio in the AudioKit project. Good job on improving the performance of these plots, by the way!

These are rather minor things compared to what we were using before, but if you don't mind merging that back then it will make it easier to keep AudioKit and EZAudio in sync from now on.

• Use const float * buffers where appropriate to indicate the original data is not being mutated and avoid some nasty casts on our side.
• Extended IBInspectable properties and marked classes with IB_DESIGNABLE
• Rewrote the RMS method using the Accelerate framework, since you now link with it it shouldn't be an issue and may even improve performance a bit further.

[syedhali]

Sweet, really appreciate this @megastep. I'll take a quick look and get these changes in later today!

[megastep]

I just found a bug that surfaced in AudioKit and included a fix for it, by the way. :)

[JanX2]

Is there a reason, why this hasn’t been merged? LGTM. :)

[megastep]

Well it's been a while so I hope this is still relevant!