Red's launcher / Downloader reqs autoinstall (#552)

start_launcher.bat

@@ -0,0 +1,35 @@
+@echo off
+chcp 65001
+echo.
+pushd %~dp0
+
+::Attempts to start py launcher without relying on PATH
+%SYSTEMROOT%\py.exe --version > NUL 2>&1
+IF %ERRORLEVEL% NEQ 0 GOTO attempt
+%SYSTEMROOT%\py.exe -3 launcher.py
+PAUSE
+GOTO end
+
+::Attempts to start py launcher by relying on PATH
+:attempt
+py.exe --version > NUL 2>&1
+IF %ERRORLEVEL% NEQ 0 GOTO lastattempt
+py.exe -3 launcher.py
+PAUSE
+GOTO end
+
+::As a last resort, attempts to start whatever Python there is
+:lastattempt
+python.exe --version > NUL 2>&1
+IF %ERRORLEVEL% NEQ 0 GOTO message
+python.exe launcher.py
+PAUSE
+GOTO end
+
+:message
+echo Couldn't find a valid Python ^>3.5 installation. Python needs to be installed and available in the PATH environment
+echo variable.
+echo https://twentysix26.github.io/Red-Docs/red_win_requirements/#software
+PAUSE
+
+:end