Update TFTv2.h

drawString produces illegible results when size = 1, the letters are fused together and some characters like lowercase i, which have only one pixel gap between the dot above the body of the i, when rendered by drawChar, result in one solid line because pixels are doubled up in the x and y direction.

added method setSpacing to control spacing between chars
added method setBold, controls doubling up of pixels in drawChar (default behavior)
added method setThin, drawchar renders a single pixel, produces very sharp results for size 1
added method setTall, pixels are doubled in the Y direction
added method setWide, pixels are doubled in the X direction, lowercase i is still legible

added private attributes spacing, widechar and tallchar to modify behaviour of drawChar, drawString

corrected spelling error in name of method drawTriangle