add .gitignore entries for junk files generated by running unit tests

.gitignore

@@ -1 +1,2 @@
 .project
+CMakeLists.txt.user

src/Unittests/.gitignore

@@ -0,0 +1,7 @@
+deleted_output.off
+output.off
+persistence-check.om
+smoothed_STL_output.off
+smoothed_custom_properties_output.off
+smoothed_extended_output.off
+smoothed_output.off

src/Unittests/TestFiles/.gitignore

@@ -0,0 +1,6 @@
+cube-minimal-customprops_openmeshOutputTestfileBinary.ply
+cube_floating.off
+cube_floating_binary.off
+meshlab_binary.ply
+meshlab_binary_float.ply
+meshlab_float.ply