Store copy of changed object in _markFieldChange()
Store copy of changed object in _markFieldChange()

Otherwise a splice() on a stored array affects the calculation of what's
new.

gracile-fr/zotero,gracile-fr/zotero,retorquere/zotero,rmzelle/zotero,hoehnp/zotero,retorquere/zotero,rmzelle/zotero,hoehnp/zotero,retorquere/zotero,gracile-fr/zotero,hoehnp/zotero,rmzelle/zotero