Goto next/previous diff commands + minor cleanups (#2759)

* Comment fix & gofmt fix

* Goto next/previous diff commands

These commands will work in `git` repositories or whenever `set diff on` is
working. They are bound to `Alt-[` and `Alt-]` by default. I would prefer
`Alt-Up` and `Alt-Down`, but that's already taken.

There are no tests at the moment; I'm looking into writing some since that will
be needed for the rest of the plan to make
https://github.com/zyedidia/micro/discussions/2753 a reality. I'm not sure how
difficult that will be.

* Realign JSON in keybindings.md

internal/action/actions.go

@@ -1027,6 +1027,28 @@ func (h *BufPane) FindPrevious() bool {
 	return true
 }
 
+// DiffNext searches forward until the beginning of the next block of diffs
+func (h *BufPane) DiffNext() bool {
+	cur := h.Cursor.Loc.Y
+	dl, err := h.Buf.FindNextDiffLine(cur, true)
+	if err != nil {
+		return false
+	}
+	h.GotoLoc(buffer.Loc{0, dl})
+	return true
+}
+
+// DiffPrevious searches forward until the end of the previous block of diffs
+func (h *BufPane) DiffPrevious() bool {
+	cur := h.Cursor.Loc.Y
+	dl, err := h.Buf.FindNextDiffLine(cur, false)
+	if err != nil {
+		return false
+	}
+	h.GotoLoc(buffer.Loc{0, dl})
+	return true
+}
+
 // Undo undoes the last action
 func (h *BufPane) Undo() bool {
 	h.Buf.Undo()
@@ -1311,7 +1333,7 @@ func (h *BufPane) OpenFile() bool {
 	return true
 }
 
-// OpenFile opens a new file in the buffer
+// JumpLine asks the user to enter a line number to jump to
 func (h *BufPane) JumpLine() bool {
 	InfoBar.Prompt("> ", "goto ", "Command", nil, func(resp string, canceled bool) {
 		if !canceled {

internal/action/bufpane.go

@@ -708,6 +708,8 @@ var BufKeyActions = map[string]BufKeyAction{
 	"FindLiteral":               (*BufPane).FindLiteral,
 	"FindNext":                  (*BufPane).FindNext,
 	"FindPrevious":              (*BufPane).FindPrevious,
+	"DiffNext":                  (*BufPane).DiffNext,
+	"DiffPrevious":              (*BufPane).DiffPrevious,
 	"Center":                    (*BufPane).Center,
 	"Undo":                      (*BufPane).Undo,
 	"Redo":                      (*BufPane).Redo,

internal/action/defaults_darwin.go

@@ -41,6 +41,8 @@ var bufdefaults = map[string]string{
 	"Alt-F":          "FindLiteral",
 	"Ctrl-n":         "FindNext",
 	"Ctrl-p":         "FindPrevious",
+	"Alt-[":          "DiffPrevious|CursorStart",
+	"Alt-]":          "DiffNext|CursorEnd",
 	"Ctrl-z":         "Undo",
 	"Ctrl-y":         "Redo",
 	"Ctrl-c":         "CopyLine|Copy",

internal/action/defaults_other.go

@@ -1,3 +1,4 @@
+//go:build !darwin
 // +build !darwin
 
 package action
@@ -43,6 +44,8 @@ var bufdefaults = map[string]string{
 	"Alt-F":          "FindLiteral",
 	"Ctrl-n":         "FindNext",
 	"Ctrl-p":         "FindPrevious",
+	"Alt-[":          "DiffPrevious|CursorStart",
+	"Alt-]":          "DiffNext|CursorEnd",
 	"Ctrl-z":         "Undo",
 	"Ctrl-y":         "Redo",
 	"Ctrl-c":         "CopyLine|Copy",