Rate Tables; several fixes and enhancements for tiered Rate Tables

Several fixes and enhancements for tiered Rate Tables have been made.

1. Whilst editing the rates the "From" column was not immediately updated when the "To" column value is changed.

2. Moving rows up and down using Ctrl+Up or Ctrl+Down keys did not update the "From" column.

3. Added Move Row Up and Down buttons below the grid.