changes in UTF-8 patch

[Rostislav Beneš <xbenes5 fi muni cz>]

I have made some improvements of my UTF-8 patch.

full support of combining marks:
- corrected computing width of string
- added functions in api: str_next_noncomb_char, str_prev_noncomb_char,  
str_iscombiningmark, used in WInput, view, search in panel
- comparing functions normalize all strings at the begin. Most of them  
works with invalid strings.

move/copy/delete dialogs do not replace invalid sequences in strings.
- do not replace invalid sequences with question marks, original values  
are preserved. Even if destination is in different encoding. (Is possible  
to convert invalid  file name)

some inner changes in api functions, two functions renamed:
str_real_charpos -> str_offset_to_pos
str_termpos_to_charpos -> str_column_to_pos
marked function, that accept invalid strings

view has better move to match function (in text mode of course)

links:
http://www.fi.muni.cz/~xbenes5/projects/mc/mc-utf8.tar.gz
http://www.fi.muni.cz/~xbenes5/projects/mc/mc-utf8-all.tar.gz
http://www.fi.muni.cz/~xbenes5/projects/mc/mc-complete.tar.gz