Add Pointcloud / plyfile support to Bonn

[matthewspear]

• Add parameter to load plyfile with BONNReader
• Add tinyply dependency to handle reading ascii plyfiles
• Add function to convert plyfile to slambench pointcloud
• Updated makefile to support plyfile

[matthewspear]

Stats

Groundtruth Subsection:

• 2.3GB on disk as .ply
• Reading took 74.6424 seconds
• Read 54676774 total points

Groundtruth Full:

• 16.4GB on disk as .ply
• Reading took 511.208 seconds
• Read 394109339 total points

As expected trying to load full groundtruth crashes after running out of memory:

terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
Aborted (core dumped)

[matthewspear]

Pointcloud displays in Pangolin (light blue):

But struggles to run properly due to the renderer or possibly my computer!

[matthewspear]

I think that is everything @mihaibujanca, let me know if anything else needs changing!

[mihaibujanca]

Nice work, just tested it