MEP converter fixes
Three issues are addressed:
- When multiple input files are specified, read them in order from first to last
- convert ODIN to v7 instead of setting only the version to v7
- Fix event counting
- when moving to the next input file
- when decompression fails
The last point ensures that MEPs have exactly the packing factor that is specified on the command line.
It seems that a few events per 10k input events fail to decompress.