Fix for NDPI files over 4GB

[sderaedt]

Fix for error: "Can't validate JPEG for directory 0: Expected marker at ..., found none"

This fixes issue #174

[geektortoise]

Hello,
Thanks for this PR.
Did the metadata read well on your test cases ?
As said in the issue 174, I get strange metadata values :/

[ntempier]

Hello,
I installed the last git version but it still does not want to open my > 5 Go files, did you manage to do something about it ?
Best,

Nicolas