(WIP) Store uid and gid in the database, instead of names. That replaces the owner and gr_name attributes with uid and gid.

Note: wildcards in config files for "owner" and "group" are no longer supported because only numerical uid/gid are handled internally.
Change the way operation entries are allocated. This avoids a copy of the structure, and open the way to have a pool of free entries that can be re-used. Replace InitEntryProc_op by EntryProcessor_Get. When initializing the entry op, do not set the fields to 0 since the structure has already been zeroed out. EntryProcessor_Push no longer copies the entry, and now will always be successful.
Instead of pushing the op to the pipeline, let the changelog reader accumulate them for a while. Once enough are there, browse the list and try to push to the pipeline those that are old enough, or if there is too many in the queue.

That way if might be possible to ignore some of the record we can't normaly ignore. For instance if a CREATE is followed by a CLOSE, the CLOSE can safely be removed since RH will do for the CREATE will it would have done for the CLOSE. This optimization is only possible if neither have been processed by the pipeline.

Added 3 new config options to the changelog reader:
- queue_max_size: size of the internal operation queue; do not keep more than this number of operations
- queue_max_age: do not keep operations older than this many seconds
- queue_check_interval: check whether some operations in the queue should be flushed at this interval
Extract the id constraint hash implementation and make it more generic so it can also be used by the changelog reader.
Use a hash table to keep track of changelog record with same id instead of browsing the whole op_queue.
Fixed test 106
Fixed typos.
The changelog operation type is unsigned. Also, no need to convert the type to a string to see if it's valid; use CL_LAST for that.
tests/lustre_fs/report.out is a generated file. Remove it.
(WIP) Re-organize the changelog reader to process the renames diffently.
If a CL_EXT is expected, temporarily store the CL_RENAME record.

The code is still doing UNLINK/RENAME/EXT, but eventually RENAME and EXT will be collapsed.

This fixes test 108b.