future info: unit flags4

[ab9rf]

per putnam unit.flags4 & 8192 will be added in a future release to handle the case of a unit whose last pathfinding attempt failed, indicating that it should attempt to climb or jump at its next opportunity

for version-tracking purposes, related code in 50.09 (steam) may be at 0x140a323c0 and/or 0x14107ff40; these 50.09 functions should be version-tracked into 50.10 if possible to investigate changes in behavior in these functions when 50.10 is released

[quietust]

Added as "path_failed_recently", along with "portrait_must_be_refreshed" for 16384