Create a Point Cloud Mesh type

[griestopf]

The Point Cloud Mesh type mapping (more or less) 1:1 the point data and attributes as defined in the potree point type.

[wrestledBearOnce]

Note: If I read the source code correctly, the Potree point type contains all LAZ-attributes, if necessary.

See: https://github.com/potree/PotreeConverter/blob/develop/Converter/include/PotreeConverter.h#L136

and some other places, where these values are being saved and converted. Therefore, we should discuss which types we want to support, too

[wrestledBearOnce]

@wrestledBearOnce creates a laz file with all attributes

[ASPePeX]

Obsolete since #622