Russian charsets and functions

[David Relson]

With Evgeny's latest modifications, "#ifdef CP866" controls the
inclusion/exclusion of the following function, tables, etc.

I'm willing for bogofilter to include all the language tables.  However
there are multiple, conflicting table entries and mapping functions.  If
someone who knows more than I do would care to provide direction, it'd
be helpful.

Functions:

    static void map_cp866(void);
    static void map_iso_8859_5_to_cp866(void);
    static void map_koi8_r_to_cp866(void);
    static void map_windows_1251_to_cp866(void)
    static void map_windows_1251_to_koi8r(void);
    int  decode_and_htmlUNICODE_to_cp866(byte *buf, int len)

Byte Arrays:

    static byte cp1251_to_cp866[] = {
    static byte koi8_r_to_cp866[] = {
    static byte iso_8859_5_to_cp866[] = {

Named Charsets and Maps:

    "cp866"          &map_cp866
    "cp866"          &map_windows_1251_to_cp866
    "iso8859-5"      &map_iso_8859_5             /* ISOIEC 8859-5:1999 LatinCyrillic Alphabet */
    "iso8859-5"      &map_iso_8859_5_to_cp866    /* ISOIEC 8859-5:1999 LatinCyrillic Alphabet */
    "koi8-r"         &map_koi8_r_to_cp866
    "windows-1251"   &map_windows_1251
    "windows-1251"   &map_windows_1251_to_cp866
    "windows-1251"   &map_windows_1251_to_koi8r