Compiling tris2indicator on Linux Ubuntu 16

change code from MapViewOfFile (Windows) to mmap (Linux) on read_obj.cpp and write_grid.cpp.

$g++ read_obj.cpp vect.cpp global.cpp insert_poly.cpp write_grid.cpp timer.cpp main.cpp -lpthread -lm -o tris2indicator



source code:
[1] http://josiahmanson.com/research/wavelet_rasterization/