Added 'Peaks' analysis

re-using & re-applying the laundry approach to look at distribution of
activities over time & especially the components of ‘Peak Demand’
periods
updated readme
amended laundry

changed half-hour aggregation to include:
- tables of counts of episodes starting in a given half hour (misses
the duration of long episodes)
- sampled episodes every 10 minutes to produce ‘slots’
updated peaks script

2 methods of summarising to half hours:
1 - count the episodes that start in a given 1/2 hour (this
underestimates prevalence of long duration activities but seems OK for
short duration ones)
2 - sample episodes at time t (e.g. every 10 minutes), record act,
aggregate per diarypid and then re-convert to long file
updated half-hour aggregates

Implements same methods as ‘Peak’:
1 - count episodes starting in a given 1/2 hour
2 - sample episodes at time t, aggregate to diarypid & reform to long
file
updated half hour sampling codes

now works!!
amended laundry script