`ai_get_weapon` is not guaranteed to return a valid `wip`, so check for that here. This should now cover all uses of `ai_get_weapon` in the codebase.
Fixes an Event Horizon crash reported in Discord. Follow-up to #5842, commit 8dbe0e7.
Add "tactical" versions of disable and disarm goals which only perform the specific task without implying anything else. The target ship is not protected and attack goals are not cleared from other ships.
There is also a new AI profiles flag to make this the default hud squad message command instead of the classic disable/disarm.
This initializes `mc_info` to the correct values when it is constructed, removing the need for `mc_info_init`.
This PR also fixes a group of incorrectly inverted assignments in beam.cpp.
Follow-up to #5040. This extends the checks to most iterations over `obj_used_list` in FSO. There are a few exceptions such as `waypoint_add` and `waypoint_remove`, plus a few others. And none of the object iterations in FRED have the guard because FRED does not use the same object life cycle as FSO.
When iterating through `Ship_obj_list`, check the `Should_be_dead` flag before using the object. This fixes#4990 and adds defense-in-depth checks to guard against similar errors elsewhere.
I considered moving the `Ship_obj_list` removal from `obj_delete` to `ship_cleanup`, but decided it would be prudent to avoid fundamental changes to lifecycle management.
Adds gravity! Applies on a per-mission basis, and weapons, ships, debris, and asteroids now have a configurable "gravity const" which multiplies the effect of gravity on them, by default everything except debris is 0 (meaning no effect even when the mission has gravity). AI and the lead indicator will also lead for ballistic trajectories as well, given a gravity-affected weapon. No FRED support or gravity direction control yet, to come in later PRs.
Previously, the default distance for determining if a ship had finished a point in a model path was only 5. This worked fine for ships with low damp or no Newtonian physics. However, it did not work well with ships that use higher damps or Newtonian physics, becuase those ships contiunatlly overshoot that 5 meter distance and get stuck flying in a large circle trying to reach that point. This fix allows modders to set an AI flag to specify that the path distance check uses a larger value of 775 for points that are not the last point in the path. If desired I can add a game settings option that allows modders to set this value.
Goober5000