Support for LAS file > v. 1.2

[cjcrosby]

P2G by itself presently only support LAS v 1.0-1.2 files. With USGS requiring LAS 1.4 deliverables, would be nice to support later LAS versions (1.3 and 1.4) without having to link against PDAL.

[hobu]

@cjcrosby PDAL has started bringing p2g-like functionality into the main library. A writers.gdal is now available in a branch, which we will be releasing in PDAL 1.4.0. We went this direction for a number of reasons:

• PDAL requires GDAL already
• GDAL output gives us a whole bunch of different output types
• PDAL is in Debian and Homebrew, which makes for easy consumption and use. P2G isn't in the packaging systems.
• Provided an opportunity to polish things up and get exactly what we needed.

https://github.com/PDAL/PDAL/blob/gdalwriter/io/gdal/GDALWriter.cpp