Collapsing deleted region to a single line

[thutt]

When reviewing code, large deleted regions make reading the modified code difficult because scrolling is sometimes involved. This feature facilitates collapsing the deleted region on the modified file, and the base file down to a single line. This makes reading the modified code easier.

COLLAPSED DELETED REGIONS FEATURE IMPLEMENTATION

FEATURE DESCRIPTION:

Added the ability to collapse deleted blocks of code in the diff viewer:

KEYBOARD SHORTCUTS:

• X : Collapse/uncollapse the deleted region at the cursor
• Shift+X : Collapse/uncollapse ALL deleted regions (toggle)

CONTEXT MENU:

1. Right-click on a deleted region (deleted in base, not present in modified)
2. Select "Collapse this deleted region" to collapse just that region
3. Select "Collapse all deleted regions" to collapse all deleted regions at once
4. Collapsed regions show as a single line with text like "[...5 deleted lines collapsed...]"
5. Right-click on a collapsed region marker to uncollapse, and select the appropriate uncollapse menu item.
6. Options: "Uncollapse this region" or "Uncollapse all regions"