Powershell enable ANSI / VT100 escape sequences

Enable-ANSIEscapes.ps1

# This is a total of 5 logical LOC, but the API is... well hidden and highly opaque
# (magic numbers everywhere!) so it warrents a few dozen lines of comments

function Enable-ANSIEscapes {
	# Enable ANSI / VT100 16-color escape sequences:
	# Original discovery blog post:
	# http://stknohg.hatenablog.jp/entry/2016/02/22/195644
	# Esc sequence support documentation
	# https://msdn.microsoft.com/en-us/library/windows/desktop/mt638032(v=vs.85).aspx

	# This doesn't do anything if the type is already added, so don't worry
	# about doing this every single time, I guess
	Add-Type -MemberDefinition @"
[DllImport("kernel32.dll", SetLastError=true)]
public static extern bool SetConsoleMode(IntPtr hConsoleHandle, int mode);
[DllImport("kernel32.dll", SetLastError=true)]
public static extern IntPtr GetStdHandle(int handle);
[DllImport("kernel32.dll", SetLastError=true)]
public static extern bool GetConsoleMode(IntPtr handle, out int mode);
"@ -Namespace Win32 -Name NativeMethods

	# GetStdHandle: https://msdn.microsoft.com/en-us/library/windows/desktop/ms683231(v=vs.85).aspx
	# -11 is the code for STDOUT (-10 is STDIN, -12 is STDERR)
	$Handle = [Win32.NativeMethods]::GetStdHandle(-11)

	# GetConsoleMode: https://msdn.microsoft.com/en-us/library/windows/desktop/ms683167(v=vs.85).aspx
	# get the console "mode" --- contains info about how to handle
	# wrapping, etc. $Mode is set by reference by GetConsoleMode
	$Mode = 0
	[Win32.NativeMethods]::GetConsoleMode($Handle, [ref]$Mode)
	# the mode is a bitmask so we binary or with 0x0004
	# (ENABLE_VIRTUAL_TERMINAL_PROCESSING)

	# SetConsoleMode: https://msdn.microsoft.com/en-us/library/windows/desktop/ms686033(v=vs.85).aspx
	return [Win32.NativeMethods]::SetConsoleMode($Handle, $Mode -bor 4)
}