Fixed bug (regression) related to the Issue #23 fix. The bug was that loading the file when the "prepend date on newly created tasks" option is set would prepend "(null)" to all tasks in the file.
Fixed bug that caused tasks to be duplicated when a file was reloaded while a filter is active. Closes Issue #24.
Merge branch 'feature/fix-filter-bug' into develop. Closes Issues #23 and #24.