Fixed bug that caused icy header metadata to be not correctly

encoded/converted. Characters above x7F were replaced by '?' character
although the rfc defines a ISO−8859−1 encoding for descriptive
field-content.

According to rfc2616 the field-content is defined as follows:
<the OCTETs making up the field-value and consisting of either *TEXT or
combinations of token, separators, and quoted-string>
The TEXT rule is only used for descriptive field contents and values
that are not intended to be interpreted by the message parser. Words of
*TEXT MAY contain characters from character sets other than ISO- 8859-1
only when encoded according to the rules of RFC 2047.

In the previous implementation the icy metadata was converted based on
fromcode "ascii".

Following incoming icy header field-values should be encoded as
"ISO−8859−1" before adding them to the metadata structure.

- misc.c unicode_fixup_string enhanced by an additional parameter to
define the fromcode
- misc.h unicode_fixup_string prototype updated
- filescanner.c function fixup_tags updated to stay compatible to the
previous implementation using fromcode "ascii"
- db.c function unicode_fixup_mfi updated to stay compatible to the
previous implementation using fromcode "ascii"
- http.c function metadata_header_get enhanced to encode the header
field-content as "ISO−8859−1" to comply with rfc2616

src/filescanner.c

@@ -588,7 +588,7 @@ fixup_tags(struct media_file_info *mfi)
       /* fname is left untouched by unicode_fixup_mfi() for
        * obvious reasons, so ensure it is proper UTF-8
        */
-      mfi->title = unicode_fixup_string(mfi->fname);
+      mfi->title = unicode_fixup_string(mfi->fname,"ascii");
       if (mfi->title == mfi->fname)
 	mfi->title = strdup(mfi->fname);
     }