also with some i18n update

Using NLog as the logger

No wrapper is used since we would use NLog for some time.
Currently the UI is not fully ready to select all log levels.

Fix #2782

https://github.com/shadowsocks/shadowsocks-windows/issues/2657

Support Windows 10 1903 Light Theme

But Fix Support Windows 10 1903 Dark Theme

Support Windows 10 1903 Light Theme

Fixed bug of #2379 pullrequestreview-254461303
Redundant paintings when user move mouse on the icon, pixel by pixel.

Move GetWindows10SystemThemeSetting() to Util.cs
WindowsThemeMode use enum
Status var windowsThemeMode rename to windowsThemeMode
Used `if else` to replace `switch case`
Delete legacy commint (Some code).
Increase contrast for icon.

Add new hints and fixed some old interaction bugs

Support Windows 10 1903 Light Theme (Menu icon color)

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"

* 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>

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>

Design:

Use the plain string for both config and hotkey parsing
and make use of KeyConverter, ModifierKeysConverter
to make it more rubust.

Find corresponding label (to display operation result) and callback (to do the real work) based on textbox name. In this case, they should be named as `<Feature-Name><Control-Name>`.

ShowLogsTextBox,
ShowLogsLabel,
ShowLogsCallback.

If this requirement doesn't meet, throw an exception at runtime.

Logic:

How to input keys:
1. put focus in the corresponding textbox
2. press the key combination you want to use
3. when you think it is ready, release all keys
4. the textbox shows your input

How to change keys:
1. put focus in the corresponding textbox
2. press BackSpace to clear content
3. re-input new one

How to deactivate:
1. clear content in the textbox
2. press OK button

Meaning of label color:
- Green: this combination is not occupied by other programs and register successfully
- Yellow: this combination is occupied by other programs and you have to change to another one
- Transparent without color: initial status

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

- Only use one instance of LogForm

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

- Revert bandwidthScale when throughput gets smaller
- Don't save coordinates when LogForm is minimized. Otherwise, we get negative values
- activate ConfigForm & ProxyForm & LogForm

User requested.

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

- use null conditional access in case some connections been
  cancelled unexpectedly and may cause null reference exception
- Refine error message
- use conditional operator to simplify some code

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