more vector functions
Fixed conflicts
Remove copy function (use clone, the default one), fixed vectors in body.lua, fixed ugly name in selector.lua
Better selection

Changelog:
I. body.lua:
	- new centerX,Y, Vx,y "getters" and "setters"
	- new useful ispointinside function (may change name)
	- changed move_to to use :normalized() (may go back to atan2, sin and cos
again)
II. character.lua:
	- radius is no more (you can actually use it but it will be changed to a
normal size)
	- position is now top-left (instead of center)
	- each character has it's own 'marker' (better for when there are two
distinct destinations, also, relieves selector of some work)
III. selector.lua:
	- no more 'global' marker
	- better selection: you can now click to select
	- prettier selection box

TODO: Add ctrl-select
Changed var names to something LOGICAL & more!

Changelog:
 1. Body:
  - move_to uses look_at again.
  - ispointinside renamed to is_inside.
 2. Selector:
  - Multi-selection with lshift.
  - If selected already contains the selected body, deselects it.

Issues and Bugs:
 - None that I know of so far.
TODO:
 - Multi-movement.
Improved vector
add,sub,div and mult methods will now return the vector itself.
Also, a new :normalize() method
Camera commit.

Changelog:
 1. Camera
  - Translation (arrow keys)
  - Zoom in/out (mouse wheel)
  - Rotation (middle mouse button + mouse wheel)
 2. Selector
  - Added support to camera

Issues and Bugs:
 - Scaling is not centered nor follows mouse.
 - Rotation, although centered, does not yet have support to selector.

TODO:
 - Scale must follow mouse.
 - Rotation must be supported by Selector.