Changes in synchronization callbacks

- Call all syncupdate_remote_* callbacks (previously unimplemented)
- Provide all callbacks in both ways: when the origin of the event is
local and when it's remote
- Provide the Sync object in all callbacks
- Provide the LocalNode object for callbacks related to local changes
- Provide the Node object for callbacks related to remote changes
- Provide the full path when directly available (to gain performance
avoiding to construct it again)
- New callback for remote renames
- Provide the previous name for remote renames
- Provide the previous parent for remote moves
- New interface in the intermediate layer to provide sync events to apps
- Reset the changed flag of nodes after being notified
- Updated megacli and megasimplesync