Added `Vector2` with typical lines
Added `Vector2` struct
Added Vector2::`x, y` fields
Added Vector2 constructors declaration for:
  -pair of coordinates;
  -scalar
Added constexpr qualifier for constructors;
Added bunch of useful `inline static constexpr` methods :P
Added bunch of arithmetical operators declaration
Added some more operators!
Added bunch of useful math methods declarations...
Added normalize method
Added bunch of static methods from MonoGame::Vector2
nothing, just skip this commit
Added Vector2 source file with some typical lines
Added Vector2 constructors definition
Deleted default values for Vector2(double, double) constructor
Gash, overrestricted, screw constexpr!
s-s-s-s-screw constexpr! So many compile errors!
Deleted constexpr from constructors;
Added operators definition
Added some more operators definition;
Added bunch of headers
Added MathHelper from old vulture;
Added some more definitions!

/*Oh god, these are so boring;
 *Im just sitting here,
 *commiting code that was writed
 *looong time ago
 */