Misc minor updates and fixes

[roninsightrx]

• misc minor bugfixes in data collection
• adds "middle" (or "cmid") timepoint
• adds "random" timepoint
• adds "scatter=" option to induce random scatter in timepoints

[roninsightrx]

theoretically we could use this scatter argument to account for non-exact dosing too.

Ah yes, good point. Larger change though, could be tackled in different ticket.