move diffParser to MathExpression.parse
move diffParser to MathExpression.parse

ChristopherChudzicki/math3d,stardust66/math3d,ChristopherChudzicki/math3d,stardust66/math3d,stardust66/math3d,ChristopherChudzicki/math3d,ChristopherChudzicki/math3d,stardust66/math3d