Improve macros using procedural macros #7
Description
The current macros (like length, angle, point, dir) are working for now, but can probably be improved using procedural macros.
- length and angle could be used without the weird space between value and unit (like angle!(45deg) instead of angle!(45 deg))
- point could become more flexible by allowing more combinations between expressions and straight values
- dir could be more consistent by raising a compile error on any zero value, not just 0 and 0.