* src/header.c (get_header): [BUG] Could not read level 2 header

* src/header.c (get_header): [BUG] Could not read level 2 header
when the header size is grater than 256.
(convert_filename): Should use the `FILENAME_LENGTH' macro rather
than 256.
(write_header): [BUG] Suppress to overflow the header size when
long filename is written in level 0 or 1 header. On level 1
header, always use the extended filename header instead of the
base header.

git-svn-id: svn+ssh://svn.sourceforge.jp/svnroot/lha/lha/trunk@374 6a8cc165-1e22-0410-a132-eb4e3f353aba