Automatically move units away from construction sites

[Philip]

Currently you can't place a new building if there's any unit in the way, and it immediately blocks all movement through its area.

From here:

what ought to happen ![...] - units are ignored when placing the foundation, then it tells friendly units to get out of the way and blocks them from walking over the foundation any more, and a builder can get the building to above 0% build progress once there's no units in the way (including enemy units), and after that point the foundation blocks enemy units walking over it too. (That avoids your own units blocking the building, but also avoids the exploitation of foundations to block enemies).

[anonymous]

Milestone Unclassified deleted

[philip]

(In [8899]) # Support AI construction of buildings. Pass terrain passability data to AI scripts. Expand pathfinder passability data to 16 bits per tile, to allow more classes. Support 16-bit ints in serializer. Partially support JS typed arrays. Allow foundations to be placed on top of units (fixes #499). Stop farms and fishes blocking movement (fixes #534). Add obstruction flags to allow finer control over what they block. Associate entity IDs with obstruction shapes, to allow finding colliding entities. Support moving to the edge of a target entity with inactive obstruction. Support foundation entities in AI. Support playing as non-hele civs.