Table cell/row/column selection – stage III (optional features)

[jodator]

This is a followup for the table selection optional features (after stage II: #6285).

• Pasting table into a selected table fragment (bigger then one cell) #6120: Pasting table into a selected table fragment (bigger than one cell)
  • Handle case of a smaller table pasted into bigger selection #6769: Handle case of a smaller table pasted into bigger selection
• Pasting table when only one table cell is selected #6121: Pasting table when only one table cell is selected
• Handling spanned cell in pasting scenarios #6122: Handling spanned cell in pasting scenarios
• Table selection with keyboard #6115: Table selection with keyboard
• Multiselection breaks in tables while holding Shift key #6453: Multiselection breaks in tables while holding Shift key
• The live preview of the table cell background should work with multiple-cell selection #6446: The live preview of the table cell background should work with multiple-cell selection
• The arrow next to the "merge cells" button seems to be disabled #6631: The arrow next to the "merge cells" button seems to be disabled