implement BODMAS order

[SignpostMarv]

While testing #6, the cause was found to be TokenScan not implementing BODMAS order & instead doing left-to-right order.

workaround is to use parenthesis.

e.g. $((11 * (15*0.707143)) * 1) - 11 * (15*0.707143)$ with left-to-right order is treated as $(((11 * (15*0.707143)) * 1) - 11) * (15*0.707143)$ when it should be treated as $((11 * (15*0.707143)) * 1) - (11 * (15*0.707143))$ with bodmas.

[SignpostMarv]

Issue deemed too much effort for little value when users can just use parentheses instead of ambiguous operation order.