Row and column resizing

[pladams9]

Current draft of this feature.

Will close #4

Issues that still need to be resolved:

• [x] Resize preview line is broken up by cell labels - Moved to issue #43
• [x] Resize preview line should be set to fill just the current window
• [x] Cell borders disappear during certain resizes
• [x] Save row/columns sizes as a part of file

[pladams9]

Broken resize preview lines

This is happening because the cell text for each cell is a label in a window. Windows are drawn above everything on a canvas.

Cell text should be changed to use a text canvas item so that it works like other canvas items. A the same time, text items should only be created for cells that have text in them. This might speed things up some (both using less items and not using full label widgets).

Label widgets and windows were used originally to allow the label to easily be cut off to a specific square. A new way will need to be worked out... possibly just reducing the number of characters in each text item based on size.

[pladams9]

Disappearing cell borders

When resizing, some borders start disappearing. It appears to happen to the bottom border of inter-row cells when the above row is too tall.

[pladams9]

Cell border issue ended up being related to broken line issue - the cell text labels were overlapping certain borders due to having the height of the row above. Fixed height issue.