Code quality remarks

[jpcima]

Grain:

• prefer FP multiplication over division when operand is constant
  example: replace / 2.0 with * 0.5
• avoid conditionals inside the frame loop (aka branches or ifs)
  

  fabric/Grain.cpp

  Line 27 in 9a16da3

  for (int framePos = 0; framePos < frames; ++framePos)

• tabulate the cosine function over the range it's ±pi/2, to accelerate the window calculation
• stop processing the frame loop early, as soon as the grain finished playing #3

GrainPlayer:

• use a pair of linked lists (used/free) for grains; don't loop the whole array #5

fabricDSP:

• don't use system-provided rand, but implement a simple LCG
  when modulo is chosen as 2^32, compute it on uint32 and omit the modulus operation
  https://en.wikipedia.org/wiki/Linear_congruential_generator#Parameters_in_common_use
• the audio buffer should be reallocated, and possibly resampled, in the sampleRateChanged method
• implement getUniqueId with appropriate char code

Mathf:

• lerp can be rewritten with one less operation
  a * (1.0 - f) + (b * f); replaced with a + f * (b - a);

General:

• initialize scalar instance variables, to the relevant default or {}, preferably in the declaration rather than constructor (example float sides {};)

NanoVG:

• close the path first, then draw it.
  eg. following code is nonsense, but most likely fill() closes the path by itself, making the next one redundant
  fill(); closePath();