v0.1.0: Add individual point timing offset calculations

Finding the precise timestamp for each individual lidar measurement
by calculating the timing offset from the timestamp of the packet.

v0.0.2: Simplify VLP-16 packet parsing

The reason for this change is to enable an easy way to produce mock
VLP-16 serialized data in tests, using a single call to binary.Write.

However, this change also ensures that the Packet struct models
byte-for-byte an on-the-wire VLP-16 packet, which simplifies parsing to
a single binary.Read call.

Initial release

Add spherical point cloud

Get structured point cloud data from decoded data packet.