PCRE version from requirement to recommendation
merged branch Tobion/patch-5 (PR #68)

This PR was merged into the 2.1 branch.

Commits
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f048e81 PCRE version from requirement to recommendation

Discussion
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PCRE version from requirement to recommendation

symfony/symfony#6062
updated license year
Merge branch '2.1'

* 2.1:
  updated license year
  PCRE version from requirement to recommendation