[fixes #2542] Fix accidental index invalidation

Fixed an invalid index that was unexpectedly caused when the configuration was abandoned, resulting in an list box index exception.

Refine PAC server

- Uncompress the text file for better version control
- Touch the PAC files in first place

- Split the file operations to new PACDaemon
- More precise matching logic for handling PAC content http request

Update the PAC file using the proxy channel only when proxy mode is enabled.

Fix shadowsocks/shadowsocks-windows/#2458

* Fix shadowsocks/shadowsocks-windows/#2458

* Servers List Box position adjustment is consistent with the v4.1.6 version

Support Windows 10 1903 Light Theme

When launch from test framework, the Application.StartupPath looks like "C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO\2019\COMMUNITY\COMMON7\IDE\EXTENSIONS\TESTPLATFORM" which may not have write permission.

Support local IPv6 listener

# Conflicts:
#	shadowsocks-csharp/Model/Configuration.cs

Turn off per-monitor DPI awareness as it is not supported

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.

Added Config Form hint text

Add new hints and fixed some old interaction bugs

Fix udp relay

fixed issue #2371

Support Windows 10 1903 Light Theme (Menu icon color)

Plugin arguments tooltip

When error code is SocketError.AccessDenied/10013(WSAEACCES), the port is reserved by system and you may not find the process name in `netstat`.
 https://github.com/shadowsocks/shadowsocks-windows/issues/1835#issuecomment-453528715