doxygen: various warning fixes

doxygen: various warning fixes

Fixes such warnings:
mc/src/viewer/mcviewer.h:1: Warning: the name `view.h' supplied as the second argument
                            in the \file statement is not an input file
mc/vfs/vfs.c:267: Warning: explicit link request to 'op' could not be resolved
mc/src/strescape.c:219: Warning: Found unknown command `\params'
mc/src/strescape.c:153: Warning: Found unknown command `\params'
mc/src/strescape.c:187: Warning: Found unknown command `\params'
mc/src/strescape.c:219: Warning: Found unknown command `\params'
mc/src/strescape.c:153: Warning: Found unknown command `\params'
mc/src/strescape.c:187: Warning: Found unknown command `\params'
mc/vfs/fish.c:33: Warning: explicit link request to 'sh' could not be resolved
mc/vfs/fish.c:33: Warning: Found unknown command `\host'
mc/vfs/ftpfs.c:43: Warning: Found unknown command `\hobit'
mc/vfs/sfs.c:26: Warning: explicit link request to 'ugz' could not be resolved
mc/vfs/vfs.c:267: Warning: explicit link request to 'op' could not be resolved
mc/vfs/vfs.c:267: Warning: explicit link request to 'op' could not be resolved

Signed-off-by: Sergei Trofimovich <slyfox@inbox.ru>