Revert "Fix renaming theme (ref #155)"

This reverts commit 785b6c6c1619947286769323bb0d77491c815664.
Revert "Migrate most of cell-based tables to view-based (ref #155)"

This reverts commit 6c8e90b133c442e3b34c3e736dbb1fbde4113b52,
but keep encoding sheets.