etc/options

--- a/etc/options	Sun Jun 06 16:34:57 2021 +0200
+++ b/etc/options	Sun Jun 06 20:29:52 2021 +0200
@@ -91,8 +91,6 @@
   -- "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)"