Update ESP8266 architecture reference
Add pushMaskedImage() to render 16bpp images with a 1bpp mask (used for transparent PNG images plus with sprites)
New functions added using drawArc:
drawSmoothArc
drawSmoothCircle
drawSmoothRoundRect
New sqrt_fraction() added to improve smooth graphics performance on processors without a FPU (e.g. RP2040)
Faster alphaBlend() function added which retains 6bpp for green
Rename swap_coord() to transpose()
82d232adfc