Frequent crashes with large number of files

[MarcosSueiro]

duplicateFields.txt

When managing relatively large files BWF ME GUI often seems slow or unresponsive, or it crashes. Today BWF ME GUI 1.3.8 crashed more than once when trying to write into 17 files less than 200 MB each. In one of them it duplicated some fields (see attached file). I am using it with option to place chunks at end of file, since it seems faster.

Windows 10 Enterprise

[JeromeMartinez]

I expect the issue to be fixed with #112.
Please test this snapshot.

[MarcosSueiro]

With ~70 files open, adding an extra one from same directory crashes BWF ME. It also seems slow when saving if ~50+ files are open