Charset convertion FROM dynamic charset is now working too
Allow dynamic charsets in CONVERT()


mysys/charset.c:
  Charset convertion FROM dynamic charset is now working too
sql/item_strfunc.cc:
  Allow dynamic charsets in CONVERT()
sql/share/charsets/cp1251.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/cp1257.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/dec8.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/greek.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/hebrew.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/hp8.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/swe7.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/usa7.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/win1250.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/win1251.conf:
  Change 003F -> 0000 for undefinite characters
sql/share/charsets/win1251ukr.conf:
  Change 003F -> 0000 for undefinite characters