Sorry for bothering. I found how to fix it. Declaration in ColorHSV.cs should be changed to:
public ColorHSV (float h, float s, float v) : this()
public ColorHSV (float h, float s, float v, float a) : this()
instead of:
public ColorHSV (float h, float s, float v)
public ColorHSV (float h, float s, float v, float a)
Maybe it will help someone who will search the forum with this error.