Pass match_list as an argument; extend it in-place
Check for blocking last

Blocking appears to be a significant bottleneck!
Add NodeWithId to File API
Remove FindFirstNode() from TrustedSystem API

It was really, really slow.  Consider this benchmark:

python -mtimeit \
-s 'import libvtd.trusted_system;\
  ts = libvtd.trusted_system.TrustedSystem(); \
  ts.AddFile("/home/chogg/Google Drive/todo.vtd")' \
'ts.AllActions()'

On my vtd file, this goes from ~75 ms to ~20 ms.