Add /f for fast init. (#1942)

The below enables Cmder Fast Init mode for `cmd.exe` sessions.  This is more like the Cmder 1.3.5 init process.  See issue #1821 

Cmder Fast Init mode bypasses or disables the following Cmder 1.3.6+ features:

* Git root and version detection.  Defaults to `%cmder_root%\vendor\git-for-windows` if it exists.
* Path enhance validation before path modify so `%Path%` enhancements are forced.
* Recursive path add for `"%CMDER_ROOT%\bin"`
* Recursive path add for `"%CMDER_USER_BIN%\bin"` if `/c [user_config_folder` is specified.
* `/d` switch to enable debug output.
* `/v` switch to enable debug output.

Add `/f` to Cmder task as shown below t enable fast init:

_Note 1: This setting is invalid in Cmder `Powershell` and `Bash` sessions~_

_Note 2: Add `/t` also to see init timer output_

![image](https://user-images.githubusercontent.com/7318053/47957637-052e3880-df90-11e8-93ef-91e1ab696d82.png)

Cuts ~2.4 seconds off of init time.

![image](https://user-images.githubusercontent.com/7318053/47957795-45db8100-df93-11e8-8ae0-551d12c4e2dc.png)

vendor/lib/lib_git.cmd

@@ -1,11 +1,9 @@
 @echo off
 
-
 call "%~dp0lib_base.cmd"
 call "%%~dp0lib_console.cmd"
 set lib_git=call "%~dp0lib_git.cmd"
 
-
 if "%~1" == "/h" (
     %lib_base% help "%~0"
 ) else if "%1" neq "" (