Separate ordering and metric logic in Perfume parser

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We should extend the parser (for Perfume only) to separate the ordering and 
metric logic.

Previously, TIME capture groups were used for metrics that also included 
ordering information (like time does), so log lines were reordered into a 
monotonically-increasing order. Currently, log lines are never reordered: 
line-based ordering is always used.

We should allow users to specify ordering via TIME groups (which may become 
more sensible if they are renamed ORDER groups) and independently specify 
metrics in new groups (e.g., IMETRIC, DMETRIC, FMETRIC). Going forward, here is 
how Perfume should respond when users do or don't specify different group types:

If no order group and no metric group:
-- fail (we don't have a way to identify metric)

If order group and no metric group:
-- use order group for both the ordering and for metric

If no order group but have a metric group:
-- use line-based ordering and metric group for metric (this is currently the 
only option in Perfume)

If both order group and metric group:
-- use order group for ordering and metric group for metric

Original issue reported on code.google.com by tonyohm...@gmail.com on 13 Aug 2014 at 3:54