- 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>

* Add HTTP proxy support in forward proxy

Signed-off-by: noisyfox <timemanager.rick@gmail.com>

* Typo

* Throw exception if forward proxy not supported.

>_<

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

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

- Use insert instead and move to newly inserted
  item instead of the last one after operation

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

Squashed commit of the following:

commit 48eb4d8839
Author: Syrone Wong <wong.syrone@gmail.com>
Date:   Sun Sep 18 15:46:09 2016 +0800

    Drop useless interface impl

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

commit c0a4f3421a
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:58:02 2016 +0800

    Revert "Updated to meet the hint from Wongsyrone."

    This reverts commit 84c8053577.

commit 84c8053577
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:52:21 2016 +0800

    Updated to meet the hint from Wongsyrone.

commit 333ccb6d1f
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:34:52 2016 +0800

    Added duplicate button to config form.

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