DBE: fix cell border rendering
DBE: improve table editor painting performance

1) Compute cell renderer's preferred size manually;
2) Only text that can become visible gets set to EditorImpl.
DBE: use LineTokenizer instead of regular expressions in cell rendering
IDEA-131250: use console font preferences in console grid
DBE: fix keyboard shortcuts for 'Set NULL' and 'Set DEFAULT' actions
(cherry picked from commit 0202fc404b24111185812f2033ed79115ce7f253)