Envelope Generator - Don't divide by zero

[zonkmachine]

Some think it's rude so I cleaned up EnvelopeAndLfoParameters.cpp a bit. I caught this because the new reverb went NaN and things shut down when I turned up the decay.
I made const f_cnt_t minimumFrames and didn't touch the knob values even though you could give them saner minimum values but you would still need to set some of the f_cnt_t variables in EnvelopeAndLfoParameters::updateSampleVars() so I went this way instead.

In the LFO m_lfoAttackFrames also use minimumFrames.

[zonkmachine]

removed from In Progress in Release 1.2.0 RC3

Removing from RC3 project as this is nothing new and needs more time.

[Umcaruje]

@zonkmachine is this targeted for 1.2?

[zonkmachine]

@zonkmachine is this targeted for 1.2?

No. I don't think we should do any changes for 1.2 concerning NaN's and 0 divisions etc. It's not one bug and it's not introduced in 1.2 . It sucks a bit but I won't have time to work on this now.

[zonkmachine]

It's not one bug...

I had a second go at this as #3687 made debugging so much easier. The ones in the envelope seems clearly defined and straight forward to just give a minimum frame of 1.

This one is ready to be merged into master. It should clear up a couple of the NaN oriented bugs for sure.
It also makes debugging with the new WANT_DEBUG_FPE flag more practical as you currently can't start lmms with any instruments because it will give a floating point error as soon as
EnvelopeAndLfoParameters::updateSampleVars() is run.

[zonkmachine]

Some final adjustments. To test this commit I suggest compiling with and without WANT_DEBUG_FPE to see the difference.

I intend to merge this in a day.