Release v0.4.0: Spherical harmonics

• Added support for 1st & 2nd degree spherical harmonics
• Added Viewer constructor parameter to enable: sphericalHarmonicsDegree. Default value is 0.
• Updated .ksplat format to include spherical harmonics
• Added new compression level for .ksplat files (2) that is identical to (1) except spherical harmonics are compressed to 8-bit
• Various bug fixes