Merge branch 'new_star' into 'master'

Use symbol ∗ for separating conjunction.

The old choice for ★ was a arbitrary: the precedence of the ASCII asterisk * was fixed at a wrong level in Coq, so we had to pick another symbol. The ★ was a random choice from a unicode chart.

The new symbol ∗ (as proposed by David Swasey) corresponds better to conventional practise and matches the symbol we use on paper.

See merge request !21
1 job for master in 2 minutes and 47 seconds (queued for 6 minutes and 54 seconds)
Status Job ID Name Coverage
  Test
failed #1204
coq
buildjob

00:02:47

 
Name Stage Failure
failed
buildjob Test There is an unknown failure, please try again
program_logic/weakestpre (user: 4.02 mem: 493292 ko)
Makefile.coq:388: recipe for target 'program_logic/weakestpre.vo' failed
make[1]: *** [program_logic/weakestpre.vo] Error 1
make[1]: *** Waiting for unfinished jobs....
base_logic/lib/invariants (user: 5.06 mem: 493824 ko)
make[1]: Leaving directory '/builds/FP/iris-coq'
Makefile:7: recipe for target 'all' failed
make: *** [all] Error 2
ERROR: Build failed: exit code 1