Add macros from wingdi.h (e.g. RGB, GetRValue)

[hi-hori]

I would appreciate it if you could add the following macros defined in wingdi.h to CsWin32.

#define RGB(r,g,b)          ((COLORREF)(((BYTE)(r)|((WORD)((BYTE)(g))<<8))|(((DWORD)(BYTE)(b))<<16)))
#define PALETTERGB(r,g,b)   (0x02000000 | RGB(r,g,b))
#define PALETTEINDEX(i)     ((COLORREF)(0x01000000 | (DWORD)(WORD)(i)))
#define GetRValue(rgb)      (LOBYTE(rgb))
#define GetGValue(rgb)      (LOBYTE(((WORD)(rgb)) >> 8))
#define GetBValue(rgb)      (LOBYTE((rgb)>>16))
#define GDI_WIDTHBYTES(bits) ((DWORD)(((bits)+31) & (~31)) / 8)
#define GDI_DIBWIDTHBYTES(bi) (DWORD)GDI_WIDTHBYTES((DWORD)(bi).biWidth * (DWORD)(bi).biBitCount)
#define GDI__DIBSIZE(bi) (GDI_DIBWIDTHBYTES(bi) * (DWORD)(bi).biHeight)
#define GDI_DIBSIZE(bi) ((bi).biHeight < 0 ? (-1)*(GDI__DIBSIZE(bi)) : GDI__DIBSIZE(bi))
#define GetKValue(cmyk)      ((BYTE)(cmyk))
#define GetYValue(cmyk)      ((BYTE)((cmyk)>> 8))
#define GetMValue(cmyk)      ((BYTE)((cmyk)>>16))
#define GetCValue(cmyk)      ((BYTE)((cmyk)>>24))
#define CMYK(c,m,y,k)       ((COLORREF)((((BYTE)(k)|((WORD)((BYTE)(y))<<8))|(((DWORD)(BYTE)(m))<<16))|(((DWORD)(BYTE)(c))<<24)))

[mjr4077au]

I'll second the additon of some macros. I was looking for DWRITE_MAKE_OPENTYPE_TAG but it's not defined in CsWin32 so I've had to roll my own.