Handle replication of data in TIMESERIES

[pausz]

From @stuart-knock

The replication of timeseries to a vector length nodes for Q is
redundant when there is no explicit space to them. A single number
would be all that needs to be returned with mapping to nodes done
in Timeseries::fire(). The exception is for noise, where we want a
different random sequence at each point in space and typically it is applied to all nodes anyway. Sometimes the noise is applied on the border of the spatial domain to study wave fronts.

To maintain a consistent interface,
it is probably best to have the vector returned by the individual
TIMESERIES fire() methods be of length the number of nodes that the
stimulus will be applied to... Resolving this issue becomes more important for higher
resolutions of the spatial domain, where currently applying a stimulus to a single
node of a 1000x1000 grid will produce a million element vector,
rather than the single number that is required...

Add vector of indices with the subset of indices that receives stimuli ... Mmmm that sounds familiar ...
Oh, yes, there is some other very nice piece of software that has a general way to do that 😛 ...