fixed regex to filter use/require (RT83569) (reported by ribasushi)
bumped version
added more require-in-string corner test cases (suggested by Buddy Burden)
reworked 80_failig.t to TODO tests; added one about require-in-string
Merge branch 'pr/3'
Prepare eval flag.
Add accessors and tests for _optional/_mandatory.
Extract eval EXPR also in one regexp.
Replace prefixes optional_/mandatory_ with suffixes _in_eval/_out_of_eval.