Omit the main rountine in fuse-ext2.c. Otherwise using fuse-ext2 with
fuse_fs is not possible because the server framework already defines
a main routine.
Fixes#1058.
* add sync method:
Since file systems tend to have a inbuild caching mechansim we need to
sync these caches at the end of session when using the fuse_fs server.
Therefore each FUSE file system port has to implement a Fuse::sync_fs()
function that executes the necessary actions if requested.
* add symlink check
* allow to check FUSE fs initialization
This changes the private API of the FUSE implementation. The init_fs
method now has to return true if the initialization was successful and
otherwise false. All current users of the API are also changed
accordingly.
Fixes#1058.
