[UX] icons in history view

[dhirschfeld]

The icons should have tooltips as it's not entirely obvious what they mean:

I assume the +/- means lines added/removed?

The circles around the +/- seem a bit redundant/ugly? Simple + and - symbols would probably suffice and to reinforce what they mean standard green/red colours could be used too.

I'm not sure the revert / delete functionality is useful? I ~never need to delete a commit and if I wanted to revert to a particular commit I would just use git reset --hard sha. Why does the UI want a commit message to revert to a commit - what is it actually doing?

I also very rarely want to revert to a commit, but I occasionally want to checkout code at a particular commit. Rather than a revert buttom, perhaps a checkout button would be more generally useful.

In contrast, GitHub has 3 buttons:

1. Copy sha

Very useful for working alongside in a terminal

2. View diff

The most important functionality! Being tracked in #252

3. Checkout (browse) code at this sha

Also very useful to understand the state of the repo at that point in time

[fcollonval]

@telamonian @kgryte I think this can be close