Adds a new component effectively handling negative resource trickles.
Prevents resources from going negative and provides an effect for not
being able to pay.
The effect chosen for 0 A.D. is having the entity not being
controllable.
Not used in the public mod itself, but it is in quite some mods.
Based on an idea of @Nescio
Differential revision: D1323
Comments by: @Angen, (@smiley,) @Stan
This was SVN commit r25191.
