[feat] Create a filter to compute pointcloud volume
Goal
This MR creates a filter to compute the volume of a space formed by an input pointcloud and a plane.
The volume is estimated by doing integral of areas formed by scanlines and the plane.
Input
 a pointcloud
 a plane
Output
 Rasterized pointcloud w.r.t input plane
 Rasterized pointcloud display in xy plane direction
 The estimated volume
Method

Step 1: Get the input pointcloud and the plane.
The plane is used to defined which part of volume would be calculated:

Step 2: Rasterize pointcloud into a 2D grid.
The resolution is defined by
Raster resolution
. To simplify the calculate, we rotate input points onto XYplan. So, the x, y coordinates of a points is used to place the point into the grid. Then we keep one point who has the max value of z in each bin of grid. 
Step 3: Compute integral volume.
To compute volume, we compute the area of each column of grid by following the
scan direction
. The we integrate the column areas as the estimated volume.
Parameters
 [double]
Grid resolution
: the size of a raster bin. The raster size depends on the pointcloud size and the raster resolution.  [enum]
Scan direction
: direction of the integral.