EVIS: Initialize t_lookup members
EVIS: Disallow literal () in ENV variables
tests: Test other escape patterns
tests: Test NUL and parentheses in CMP0053

Also remove them from StringFileTest since they belong in Syntax.
Merge topic 'dev/faster-evis' into next

9e9104dc tests: Test NUL and parentheses in CMP0053
19b3eb38 tests: Test other escape patterns
cc4bf45a EVIS: Disallow literal () in ENV variables
942a8c45 EVIS: Initialize t_lookup members