support commit amend

[extrawurst]

new command for git commit amend

• opens regular commit popup but fills in last commit msg
• disable command in empty repositories
• see https://docs.rs/git2/0.13.6/git2/struct.Commit.html#method.amend

before we can do that we need to land #83

[MCord]

what about just adding a checkbox in the commit pop up to amend instead of committing ? many existing UI tools behave this way and this minimizes the number of commands and UI complexity.

[extrawurst]

I like the idea but we need to check if there is any good (cross platform) hotkey we can use that does not collide with the text input of the commit dialog (unfortunately not everything is possible in terminals and or crossterm).

[extrawurst]

Also I happen to know someone is working on #46 (see https://www.twitch.tv/videos/639362441) hope there is no complication touching those two issues at the same time🤞

[MCord]

what do you think about using function keys ? the stream is very cool indeed I am watching it right now !

[extrawurst]

I would say let's go for the commit popup like @MCord said and add an amend option that takes the previous msg and fills it in if the current msg is empty
what about ctrl+a to hopefully not interfere with actual char inputs?

[extrawurst]

this is what it looks now: