Blender Git Loki

Fix T47896: Scripted Expression string length limit is too short for some autogenerated expressions

While most scripted expressions are quite short (e.g. "var" or "frame + 1"),
those that are autogenerated by scripts (to take into account a wide range of factors)
may require a bit more headroom to operate in.

By doubling the maximum length here, we now make it possible to combine up to 38
3-letter variables in some linear combination (with all factors expressed to 4 dp).
That should be more than enough for anyone or anything for quite a while!

Unfortunately, this does increase memory consumption for drivers across the board.