Adds energy cost checking for firing, and makes bullet angle independent
of where a click happens (bullets always travel in a horizontal plane now).

Also added cone spread, which currently only happens in the x-z plane.
The spread amount is based on how far a click happens from the player,
which we may or may not want.  Cone angles should be below .1 for reasonable
spread amounts (0 for no spread).

Signed-off-by: odkken <odkken@gmail.com>
Reduced the cone sizes of existing weapons to 0.