Revert "Remove validation for speed"

This reverts commit 8a97fcd7df9573ca46e627277314479b9559d07e.
Revert "Remove obsolete validation test"

This reverts commit 6e558ee099e9ad24c447fd72cf1588b25812ac82.
Revert "Add note on possible segfaults"

This reverts commit 2db71c11e7ca643f076c5837128c2de5ebffed55.
Ignore build directory for testing
Update emd.cpp