* database.c: Include m17n-core.h instead of m17n.h.

* database.c: Include m17n-core.h instead of m17n.h.
(load_chartable): Use mtext__from_data.
(load_charset): Moved to charset.c
(load_database): Call mdatabase__load_charset_func instead of
load_charset.
(mdatabase__load_charset_func): New variable.
(mdatabase__init): Initialize mdatabase__load_charset_func and
Mcharset.  Don't set mdatabase__finder and mdatabase__loader.
(mdatabase__save): Use fwrite, not mconv_encode_stream.
(Mcharset): Declare it here.