Fixed an issue in arg_tovals.
Fixed error message in set_makepos.
Added support for time-series fields to flt_resample.
Added 'raw' output format to onl_write_background and online writer plugins.
Fixed wrong argument type in ParadigmSIFT and ParadigmSPoC.
Added default support for the optional .stamps time-series field.
Updated eeg_load_xdf so that it now writes both .stamps and time-synched .xmin and .xmax fields.