Use sentence case everywhere

We have not been good at consistent casing so far. Now we use 'Sentence case' everywhere. EVERYWHERE.

Also Removing 'Lc' prefix from i18n field names: the 'Lc' stood for lowercase but now that everything
is in 'Sentence case' there's no need for the distinction.

I've got a couple lower case things I've kept: namely, things that show up in parentheses.

pkg/gui/controllers/bisect_controller.go

@@ -31,7 +31,7 @@ func (self *BisectController) GetKeybindings(opts types.KeybindingsOpts) []*type
 		{
 			Key:         opts.GetKey(opts.Config.Commits.ViewBisectOptions),
 			Handler:     opts.Guards.OutsideFilterMode(self.checkSelected(self.openMenu)),
-			Description: self.c.Tr.LcViewBisectOptions,
+			Description: self.c.Tr.ViewBisectOptions,
 			OpensMenu:   true,
 		},
 	}