* add hotkey `Ctrl+Down/⌘+Down` to fetch directly
* keep translation keys of en_US in order
* add translations for zh_CN and zh_TW
* do NOT using namespace under `SourceGit`
* use `⇧` instead of `Shift` in hotkey tips
* hotkey mismatch on macOS
* hotkeys to start fetch/pull/push directly not work on macOS
* remove the hotkey of `Create Branch` context menu item
- there are other objects (such as branch and tag) also have the `Create Branch` context menu item without hotkeys
- on macOS, we already use `⌘+B` to create branch with selected commit, not `Ctrl + B`
Signed-off-by: leo <longshuang@msn.cn>
* rename `FirstParentFilterToggled` to `EnableFirstParentInHistories`
* remove `FirstParentFilterEnabled` from repo settings - it should not been saved
* move toggle button from repository toolbar to histories switcher
* tooltip translations
* new icon for `Icons.FirstParentFilter`
* extends commit graph to support `--first-parent` option
need help in two issues:
1. use better icon - I just reused the Filter icon
2. lines of merge commits are still rendered - need to skip them since they don't link to any commit when filter enabled. I didn't manage to solve by my own right now
