Added rips-zigzag; in the process caught a number of bugs in ZigzagPersistence (added check_consistency() to it)
set (targets
triangle
triangle-zigzag)
set (libraries ${libraries} ${Boost_SERIALIZATION_LIBRARY})
foreach (t ${targets})
add_executable (${t} ${t}.cpp)
target_link_libraries (${t} ${libraries})
endforeach (t ${targets})