First half of the big LOS/FOV update:<ul>

<li>FoV no longer improperly peeks around blocked corners</li>
<li>LoS is now equivalent to FoV</li>
<li>"Smart" LoS: if you can see it, you can target and project to it</li>
<li>FoV has a permissiveness setting that can be set for each level</li>
<li>Distance metrics are now consistent for FoV, AoE, and talent ranges (defaults to rounded circle)</li>
<li>fov_beam_any_angle function now uses "dx", "dy" as input instead of "angle"</li>
</ul>


git-svn-id: http://svn.net-core.org/repos/t-engine4@4368 51575b47-30f0-44d4-a5cc-537603b46e54