Port of FS327 - Support for non-ASCII characters in file name strings.

[wfpokorny]

http://bugs.povray.org/task/327

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Details

pov 3.7 Can not identify the Chinese. I give the texture map file name in Chinese, it turns out parse error.

(The title is accurate in the issue being non-ASCII characters in file name strings. Meaning anyone running in a UTF-8 environment can run into this issue if they use a non-ASCII character in a file name. Have we documented this as a known limitation I wonder?)

See attached zip: FS327.zip

[c-lipka]

For the records: I'll file this as "long-standing issue that we haven't found a simple solution to yet, so we sure don't want to tackle it in a hurry while we prepare for v3.8.0 release". It would probably make no sense without a deeper cleanup regarding character encoding anyway.