etc/options

--- a/etc/options	Thu May 13 15:52:10 2021 +0200
+++ b/etc/options	Fri May 14 21:32:11 2021 +0200
@@ -83,6 +83,8 @@
   -- "level of parallel proof checking: 0, 1, 2"
 option parallel_subproofs_threshold : real = 0.01
   -- "lower bound of timing estimate for forked nested proofs (seconds)"
+option parallel_presentation : bool = true
+  -- "parallel theory presentation"
 
 option command_timing_threshold : real = 0.1
   -- "default threshold for persistent command timing (seconds)"