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_console.cmd

@@ -1,6 +1,6 @@
 @echo off
 
-rem set args=%*
+if "%fast_init%" == "1" exit /b
 
 call "%~dp0lib_base.cmd"
 set lib_console=call "%~dp0lib_console.cmd"

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 "" (

vendor/lib/lib_path.cmd

@@ -52,6 +52,15 @@ exit /b
         set "position="
     )
 
+    if "%fast_init%" == "1" (
+      if "%position%" == "append" (
+        set "PATH=%PATH%;%add_path%"
+      ) else (
+        set "PATH=%add_path%;%PATH%"
+      )
+      goto :end_enhance_path
+    )
+
     set found=0
     set "find_query=%add_path%"
     set "find_query=%find_query:\=\\%"
@@ -85,6 +94,7 @@ exit /b
         %lib_console% debug_output  :enhance_path "AFTER Env Var - PATH=!path!"
     )
 
+    :end_enhance_path
     endlocal & set "PATH=%PATH:;;=;%"
     exit /b
 
@@ -115,7 +125,6 @@ exit /b
 :::.
 :::  path       <out> Sets the path env variable if required.
 :::-------------------------------------------------------------------------------
-
     setlocal enabledelayedexpansion
     if "%~1" neq "" (
         set "add_path=%~1"
@@ -136,6 +145,11 @@ exit /b
         set "position="
     )
 
+    if "%fast_init%" == "1" (
+      call :enhance_path "%add_path%" %position%
+      goto :end_enhance_path_recursive
+    )
+
     if "%depth%" == "" set depth=0
 
     %lib_console% debug_output  :enhance_path_recursive "Env Var - add_path=%add_path%"
@@ -155,5 +169,6 @@ exit /b
         )
     )
 
+    :end_enhance_path_recursive
     endlocal & set "PATH=%PATH%"
     exit /b

vendor/lib/lib_profile.cmd

@@ -1,6 +1,5 @@
 @echo off
 
-
 call "%~dp0lib_base.cmd"
 call "%%~dp0lib_console"
 set lib_profile=call "%~dp0lib_profile.cmd"