Auto register hotkeys

* Update LogForm.cs
* Update ja.txt
* Update zh_CN.txt
* Update zh_TW.txt
* Update the control name

- Naming
- Cleanup
- Move logic to controller

- Portable mode ON: executable file's folder
- Portable mode OFF: current user's temp folder

* Translation
* Environment Variables support

* Add tooltips
* Translations

Move PerPixelAlphaForm's code into QRCodeSplashForm to avoid 2 derived class of Form in same file.

Before: QRCodeSplashForm -> PerPixelAlphaForm -> Form
After: QRCodeSplashForm -> Form

Because the splash is already on the target display, the target rect doesn't need to calculate with the screen position.

"Allow Clients from LAN" --> "Allow other Devices to connect"

- update mbedtls to 2.7.0, use new md5 api
- update libsodium to 1.0.16
- static link to openssl 1.1.0g, check libsscrypto repo for detail

* Rename variable 'traffic' to 'trafficPerSecondQueue' and 'trafficInfoQueue'

* Remove class QueueLast<T> by using linq Queue.Last()

* Slight changes, such as rename, move several variables from function domain to class domain to improve performance.
Logic remains the same.

* Update the logic of copying queue from Controller to View.

* Move the TrafficInfo declaration into LogForm class

Overwise, the VS UI designer does not work.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Don't clear the textbox, focus it instead. We want the user to see the wrong input instead of a blank textbox.

Fix #926

Use singleton mode for hotkey callbacks.

If user manually deleted servers from gui-config.json

Merge 'Switch to PAC' and 'Switch to Global'

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Also, fix typo in ProxyForm

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Use readonly object as lock

Info from stackoverflow:

If I want to be sure that it will be locked for all threads inside my
application:
The lock object has to be static, if it locks access to static state.
Otherwise it has to be instance, because there's no need to lock state of
one class instance, and prevent other threads to work with another class
instance at the same time.

everyone says that the object has to be "readonly" I didn't found the
reason
Well, it doesn't have to be. This is just a best practice, which helps you
to avoid errors.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>