Append instead of prepend TLC's stdout/stderr to SpecTE because primary use case is to edit SpecTE to add trace expressions.
Append instead of prepend TLC's stdout/stderr to SpecTE because primary
use case is to edit SpecTE to add trace expressions.

Also gets rid of creating one temporary file.

[Feature][TLC][Changelog]
tlaplus/tlaplus,lemmy/tlaplus,tlaplus/tlaplus,tlaplus/tlaplus,lemmy/tlaplus,tlaplus/tlaplus,lemmy/tlaplus,lemmy/tlaplus