cu->curinfo.mat_nr appearently didn't get initialized to 0 when creating
a new curve / text object, thus assigning random material indices to
characters, which crashed when rendering.
I'm still not sure if this was the actual issue, though I'd hope so :)
For old files that crash on rendering, just enter editmode on EACH text
object, select all text, and assign a material to it.
I hope this fixes.
7de4b17263