Add sequence flag de-sync support in OBC wrapper functions

Add support for addressing possible de-sync issues when sending data from the OBC side, based on the functions described in issue #26 (closed). Of course, this diverges from the MSP protocol in the sense that duplicate data can be sent to an experiment. The solution for this issue must therefore have to option to send data without performing the seqflag de-sync check, either by a config option or by creating a completely new function (ex creating msp_obc_send_desyncchk() instead of modifying msp_obc_send()).