WL#1324 table name to file name encoding

- Encoding itself, implemented as a charset
  "filename". Originally planned to use '.'
  as an escape character, but now changed to '@'
  for two reasons: "ls" does not return
  file names starting with '.' considering them
  as a kind of hidden files; some platforms
  do not allow several dots in a file name.
- replacing many calls of my_snprintf() and
  strnxmov() to the new build_table_filename().
- Adding MY_APPEND_EXT mysys flag, to append
  an extention rather that replace it.
- Replacing all numeric constants in fn_format
  flag arguments to their mysys definitions, e.g.
  MY_UNPACK_FILENAME,
- Predictability in several function/methods:
  when a table name can appear with or withot .frm
  extension. Some functions/methods were changed
  so accept names strictly with .frm, other - strictly
  without .frm extensions. Several DBUG_ASSERTs were
  added to check whether an extension is passed.
Many files:
  table name to file name encoding
mysql_priv.h:
  Prototypes for new table name encoding tools.
ctype-utf8.c:
  Implementing "filename" charset for
  table name to file name encoding.
row0mysql.c:
  Fixing table name prefix.
mf_format.c:
  Adding MY_APPEND_EXT processing.
Many files:
  Fixing tests.
my_sys.h:
  Adding new flag to append rather than replace an extension.
m_ctype.h:
  Adding "filename" charset definition.

storage/myisammrg/myrg_create.c

@@ -33,7 +33,8 @@ int myrg_create(const char *name, const char **table_names,
   DBUG_ENTER("myrg_create");
 
   errpos=0;
-  if ((file = my_create(fn_format(buff,name,"",MYRG_NAME_EXT,4),0,
+  if ((file = my_create(fn_format(buff,name,"",MYRG_NAME_EXT,
+                                  MY_UNPACK_FILENAME|MY_APPEND_EXT),0,
        O_RDWR | O_EXCL | O_NOFOLLOW,MYF(MY_WME))) < 0)
     goto err;
   errpos=1;

storage/myisammrg/myrg_open.c

@@ -46,7 +46,8 @@ MYRG_INFO *myrg_open(const char *name, int mode, int handle_locking)
   LINT_INIT(key_parts);
 
   bzero((char*) &file,sizeof(file));
-  if ((fd=my_open(fn_format(name_buff,name,"",MYRG_NAME_EXT,4),
+  if ((fd=my_open(fn_format(name_buff,name,"",MYRG_NAME_EXT,
+                            MY_UNPACK_FILENAME|MY_APPEND_EXT),
 		  O_RDONLY | O_SHARE,MYF(0))) < 0)
      goto err;
    errpos=1;