OPLogConvert support for Overo

This provides support for Overo log files.  Right now OPLogConvert will not parse Overo logs.  They use a different format where the UAVTalk packet contains the timestamp (which also allows them to be CRCd).

From commit log:
commit af31c1999f77a7af9ddc2bc5edd71e80201272a4
Author: James Cotton <peabody124@gmail.com>
Date:   Sat Feb 2 15:01:17 2013 -0600

    OPLogConvert: Add overo flag to calling API

commit ad5b68cbbe3c2f9de8563d87e49b689410782df9
Author: James Cotton <peabody124@gmail.com>
Date:   Sat Feb 2 14:50:02 2013 -0600

    OPLogConvert: Handle multiple instance UAVOs from Overo
    
    This is a little tricky because the relative position of the
    instanceID field moves relative to the data for timestampped
    UAVTalk packets.

commit a4efdef3b04c2371ec282ea5c9d03f223cf9899d
Author: James Cotton <peabody124@gmail.com>
Date:   Sat Feb 2 14:33:30 2013 -0600

    OPLogConvert: Process wraparounds within the matlab code
    
    This is especially problematic for the UAVTalk timestamping where
    the timestamp is uint16 in ms and wraps around more frequently.
    This required adding a lookup table for which objects are single
    instance since that moves the location of the timestamp.
    
commit 457db22a6f142e0e13b8f9c2167aa3318296fe4b
Author: James Cotton <peabody124@gmail.com>
Date:   Sat Feb 2 12:38:33 2013 -0600

    OPLogConvert: Add support for Overo logs
    
    These logs are different because they use the timestamped UAVTalk
    message type (https://github.com/TauLabs/TauLabs/wiki/UAVTalk-Protcol)
    and don't include the standard logging header (4 bytes timestamp
    and 8 byte datasize).
    
    I also had to parameterize the settings for the timestamp as it
    goes from a 4 byte uint32 to 2 byte uint16.