v2.4.9

Add relative formats to --begin and --end.
The flags --begin and --end support values in the format [N] [unit] ago:
```
mrsm sync pipes --begin '3 days ago'
```
Add a second delta format (recommended to be denoted by the keyword rounded) to round the timestamp to a clean value:
```
mrsm clear pipes --end '1 month ago rounded 1 day'
```
Supported units are seconds, minutes, hours, days, weeks, months (ago only), and years.
Respect --begin, --end, and --params in show rowcounts.
The flags --begin, --end, and --params are now handled in the action show rowcounts.

bmeares / Meerschaum