Create table in global headers tab.
Fill global headers table when loading file.
Fill global headers table when loading file.
Remove option to directly edit cell values.
Add functionality to create new global headers.
Add delete button to global headers tab.
Enable/disable delete button depending on number of selected rows in headers table.
Add edit header button and enable/disable it depending on number of selected rows in headers table.
Implement deleting rows in global headers table.
Implement updating row in global headers table.
Merge branch 'global-parameters-tab'