Fix assorted bugs in contrib/unaccent's configuration file parsing.
Make it use t_isspace() to identify whitespace, rather than relying on
sscanf which is known to get it wrong on some platform/locale combinations.
Get rid of fixed-size buffers. Make it actually continue to parse the file
after ignoring a line with untranslatable characters, as was obviously
intended.
The first of these issues is per gripe from J Smith, though not exactly
either of his proposed patches.