Fix $open_mode value from constant to string

This was a bug in documentation which I fixed. It worked because `r` (if not defined) was assumed to be `'r'` (string) + E_NOTICE.
bug #339 Fix $open_mode value from constant to string (webarto)

This PR was merged into the 0.4.x-dev branch.

Discussion
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Fix $open_mode value from constant to string

This was a bug in documentation which I fixed. It worked because `r` (if not defined) was assumed to be `'r'` (string) + E_NOTICE.

Commits
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e567290 Fix $open_mode value from constant to string