add exaple and update .gitignore

.gitignore

@@ -1,5 +1,6 @@
 [Bb]uild/
 [Bb]in/
+[Ll]ib/
 .vscode/
 input/
 .cache/

Example/main.cpp

@@ -0,0 +1,30 @@
+#include <FileHandler.hpp>
+#include <IterativeClosestPoint.hpp>
+#include <KdtreeFlann.hpp>
+#include <PointCloudFilters.hpp>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+int main( int argc, char* argv[] )
+{
+  if( argc < 2 ) {
+    std::cout << "Please provide input file" << std::endl;
+    return 1;
+  }
+  FileHandler fh;
+  pointCloud pc = fh.loadXYZfile( argv[ 1 ] );
+  std::cout << "Input pointcloud size: " << pc.size() << std::endl;
+
+  Filter3D filters;
+  KDtreeFlann kdtree;
+  IterativeClosestPoint ipc;
+
+  pointCloud op;
+  filters.voxelFilter( pc, std::stod( argv[ 2 ] ), op );
+  std::cout << "Output pointcloud size: " << op.size() << std::endl;
+  fh.writeXYZfile( op, "output.xyz" );
+
+  return 0;
+}