*  Support angle brackets, and honor TEX_LEFTRIGHT_MAX_ANGLE
*  Write real error messages
*  Support Unicode symbols (probably requires help from the font side, urgh)
*  Don't use TEX_LAYOUT_SPACING for everything, just make it the default

*  Add sum and products
*  Add square roots, and honor TEX_SQRT_SLANTED and TEX_SQRT_BAR_LENGTH
*  Add vectors
*  Add limits
*  Add integrals, and honor TEX_INT_DISPLAY
*  Add matrices