rename Cas -> CAS; make BAnon notation work better

1 job for master
Status Job ID Name Coverage
  Test
failed #175
coq
buildjob

00:02:36

 
Name Stage Failure
failed
buildjob Test There is an unknown failure, please try again
Command exited with non-zero status 1
heap_lang/tests (user: 1.62 mem: 499312 ko)
Makefile.coq:328: recipe for target 'heap_lang/tests.vo' failed
make[1]: *** [heap_lang/tests.vo] Error 1
make[1]: Leaving directory '/builds/FP/iris-coq'
Makefile:3: recipe for target 'all' failed
make: *** [all] Error 2

ERROR: Build failed with: exit code 1