Fixed targeting on dead units, teleport collision

- Fixed targeting on dead units and added a new target packet
- Added collision to teleport, made it vision specific
- Exposed lua function: isWalkable(x, y)
- Fixed Ezreal E when trying to teleport to behind a wall and the
targeting range wasn't at max range
AIMesh fixes on isAnythingBetween and castRay(Sqr)

- the two AIMesh functions did not use texture coordinates, so
everything would be far out of bounds. That is now fixed.
- Removed the vector2 isAnythingBetween and just replaced it with a
castRaySqr. Because I repasted other code, should probably do this
instead.
- Committing work to pathfinder.. Nothing interesting, just debug info.
- Removed undef from PacketHandler that I saw by coincidence. Let's not
remove/replace definitions guys. Ever.
- Made direction 0 when Object is not walking
Fixed isAnythingBetween and implemented terrain in vision

- It's not perfect, but hey, it's pretty close http://prntscr.com/4u21g3
- Added translation to real coordinates in aimesh (don't use this,
dummies, it's for me :hamster:)
- Why are there emoticons in this :accept: :hamburger: :camel:
:kissing_heart: