#1053 Increase Java heap space for Maven build from 1 to 3 GiB.
- This should fix the out of memory errors due to lack of Java heap space. At least, I hope tripling it is enough. I didn't increase to 4 GiB, since we need room for stacks, string pools, JIT-compiled code, loaded classes, and so on, that are not on the heap.
- After this one is merged, existing branches and merge requests need to be uplifted before they benefit from this change.
Closes #1053 (closed)