allow to change local files

- fuse/filecache:
     * add filecache_upload_patch
     * allow opening files in modes other than RDONLY
 - fuse/hashtbl:
     * add folder_tree_upload_patch
 - fuse/operations:
     * allow opening files in modes other than RDONLY
     * add members to private context which allow tracking of
       not-yet-uploaded files and files opened for writing and
       files opened in read-only mode
 - mfapi/apicalls/upload_patch:
     * supply x-filename and x-filesize headers
 - mfapi/apicalls/upload_simple:
     * do not supply the x-filehash header as it is not used by the
       server
 - utils/hash:
     * hex characters must be lower case for the server
 - utils/strings:
     * clean up unused functions strdup_join, strdup_substr,
       string_chomp
 - utils/stringv:
     * complete rewrite with different string vector implementation

utils/strings.h

@@ -24,13 +24,6 @@
 
 char           *strdup_printf(char *fmt, ...);
 
-char           *strdup_join(char *string1, char *string2);
-
-char           *strdup_subst(char *string, char *str_old, char *str_new,
-                             unsigned int max);
-
-void            string_chomp(char *string);
-
 char           *string_line_from_stdin(bool hide);
 
 #endif