feature: vector.rotate method accepts angle inputs
feature: vector.rotate method accepts angle inputs

resolves issue #29
fix for incorrect vector inverse transform

haithemaraissia/PhysicsJS,mcanthony/PhysicsJS,rohit765/PhysicsJS,eric-seekas/PhysicsJS,VANITAX/PhysicsJS,Luwdo/PhysicsJS,Rawneed/PhysicsJS,eric-seekas/PhysicsJS,VANITAX/PhysicsJS,Rawneed/PhysicsJS,Luwdo/PhysicsJS,Nayar/PhysicsJS,rohit765/PhysicsJS,jpellerin/PhysicsJS,haithemaraissia/PhysicsJS,pietro909/PhysicsJS,131/PhysicsJS,Nayar/PhysicsJS,griever989/PhysicsJS,aldeed/PhysicsJS,pietro909/PhysicsJS,griever989/PhysicsJS,jpellerin/PhysicsJS,aldeed/PhysicsJS,wellcaffeinated/PhysicsJS,mcanthony/PhysicsJS,wellcaffeinated/PhysicsJS