let mdhim_basem_t be first variable in all kinds of messages

so it will be easier if expanding base message type in future.
Merge pull request #10 from ZhangZhenhua/msgbase

let mdhim_basem_t be first variable in all kinds of messages
some trivial changes
return SUCCESS if failing read manifest file

If it's the first time to create/open one database, the failure is then
expected.
Merge pull request #11 from ZhangZhenhua/typos

some trivial changes