Straighten graph lanes over multiple rows

[mstv]

Fixes #5782
Follow-up to / generalization of #9028

Proposed changes

• Straighten lanes over multiple rows
• Fix-up missing handling of RevisionGraphRow._revisionLane and RevisionGraph.GetCachedCount

Screenshots

Before	After

Remark: The part of the red branch starting at cff2c15 ending at the line with 03d75aa could be straightened, too. Though this is not detected by the current implementation because this part consists of multiple segments.

Test methodology

• manual with GE and Linux repos
• added NUnit test case

Test environment(s)

• Git Extensions 33.33.33
• Build 7835202
• Git 2.27.0.windows.1 (recommended: 2.30.0 or later)
• Microsoft Windows NT 10.0.19042.0
• .NET Framework 4.8.4300.0
• DPI 96dpi (no scaling)

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✒️ I contribute this code under The Developer Certificate of Origin.

[mstv]

These two constants could be turned into settings, which might solve #8498, too.

[gerhardol]

While I personally like options, I believe GE has too many options for most users so I will by default vote no to new options.
If this can be described well it could be added.

[gerhardol]

Instead of another panel, the column could be made resizable. I am happy with the dynamic resizing.

This could be the configuration for MaxLanes

[RussKie]

Can we detect automatically how many lanes required?

[mstv]

Can we detect automatically how many lanes required?

For this, it would not suffice to load the revisions: The graph segments must be created, which is an expensive operation. That's why it is done in chunks of at most 1500 rows on user request.

MaxLanes is a hard-coded limit. (I have not introduced it. I moved it here from RevisionGraphColumnProvider in the predecessor PR.)

[ghost]

How do you like the idea to mirror the graph vertically?
There will be one line on the right.
On the left, hide, scroll or expand the graph in a separate panel.

[mstv]

How do you like the idea to mirror the graph vertically?

Pro: The main branch would be located directly beside the commit subject.
Con: Would be very nervous when the number of graph lanes changes and the graph width is adapted automatically.
Con: I read from left to right - also the graph.

There will be one line on the right.

I do not see the benefit of showing only one line of the graph.

On the left, hide, scroll or expand the graph in a separate panel.

The whole graph can be hidden using the View menu.
Instead of another panel, the column could be made resizable. I am happy with the dynamic resizing.

[RussKie]

[RussKie]

This looks awkward: