add keybind to sort table

lots of refactoring to do so
files on disk, and files in trash interface'd so table is agnostic
model keeps track of the files now, to facilitate sorting, and updates its own rows accordingly

internal/tables/sorting/sorting.go

@@ -0,0 +1,80 @@
+package sorting
+
+import "git.burning.moe/celediel/gt/internal/files"
+
+type Sorting int
+
+const (
+	Name Sorting = iota + 1
+	NameReverse
+	Date
+	DateReverse
+	Path
+	PathReverse
+	Size
+	SizeReverse
+)
+
+func (s Sorting) Next() Sorting {
+	switch s {
+	case SizeReverse:
+		return Name
+	default:
+		return s + 1
+	}
+}
+
+func (s Sorting) Prev() Sorting {
+	switch s {
+	case Name:
+		return SizeReverse
+	default:
+		return s - 1
+	}
+}
+
+func (s Sorting) String() string {
+	switch s {
+	case Name:
+		return "name"
+	case NameReverse:
+		return "name (r)"
+	case Date:
+		return "date"
+	case DateReverse:
+		return "date (r)"
+	case Path:
+		return "path"
+	case PathReverse:
+		return "path (r)"
+	case Size:
+		return "size"
+	case SizeReverse:
+		return "size (r)"
+	default:
+		return "0"
+	}
+}
+
+func (s Sorting) Sorter() func(a, b files.File) int {
+	switch s {
+	case Name:
+		return files.SortByName
+	case NameReverse:
+		return files.SortByNameReverse
+	case Date:
+		return files.SortByModified
+	case DateReverse:
+		return files.SortByModifiedReverse
+	case Path:
+		return files.SortByPath
+	case PathReverse:
+		return files.SortByPathReverse
+	case Size:
+		return files.SortBySize
+	case SizeReverse:
+		return files.SortBySizeReverse
+	default:
+		return files.SortByName
+	}
+}