Load dssc data by size

Adds option to load_dssc_module to load only a certain amount if we load in memory with persist Adds option to boz.dask_load_persistently for the size in Gb of the dark and run data to be loaded.

Closes #84 (closed)

doc/changelog.rst

@@ -8,6 +8,7 @@ unreleased
 
     - fix :issue:`75` regarding pulse Id assignment when reading BAM data :mr:`272`
     - fix :issue:`80` regarding new bunch pattern table size when reading BAM data :mr:`279`
+		- fix :issue:`84` regarding loading only a given amount of BOZ DSSC data in memory :mr:`288`
 
 - **Improvements**