Autoscroll in pager

[psprint]

A second attempt (after #1139) to add two features:

• autoscroll in pager,
• regex matching lines colorization in pager.

In this attempt I've did what has been recommended to me previously:

• autoscroll is off by default so that tig resembles less (set pager-autoscroll = off),,
• the regex used by the line colorization can be also customized via an option color-pager-regex.

I think that running make in pager is a good use case and it could be better supported.

[psprint]

@koutcher ping. I've worked on the patch and took all suggestions into account. I wonder what chances have this PR to merge?

[psprint]

@koutcher ping :)

[psprint]

@koutcher @krobelus merge?

[psprint]

@koutcher @krobelus ping 👋

[krobelus]

autoscroll seems like an interesting feature. I don't use the pager view but I can imagine autoscroll being useful.
I think this commit should be submitted in a separate PR, without the highlighting changes.

There seems to be an off-by-one error. When I type :!git log it only scrolls until the last-but-one line; the last line is not visible.

Instead of an option, we could also implement less's F command.

[psprint]

@krobelus: I've updated the PR to cover only autoscroll feature and fixed the off by 1 error. I agree that autoscroll is useful, I'm using it all the time.

[koutcher]

Thanks. It needed a bit of rework to have things done at the proper place.

[psprint]

Thanks for merging :)