update libsqlfs submodule to get the locking and other fixes
make libsqlfs build settings in sync with libsqlfs' native build system
expose sqlfs transactions via begin & complete
update libsqlfs submodule to get block size performance enhancements
Update .gitignore
Bump libsqlfs to latest development version
Bug #250: Pass file access and creation flags to libsqlfs's write function

This allows the O_APPEND flag to be read and properly handled.