A series of functions to help process .all datafiles from the Optech ALTM 3033
as delivered by the NERC ARSF.

Two example .all files are provided.

Functions:
    lidarFilt - splits every .all file in a folder into Last and First Pulse
    lidarSite - cuts out the area required based on LL/UR corner coords for a site
    lidarPlot - shows the density of points for specified grid size