as.repeatedTrain needs to cope with trains missing spikes

[jefferis]

> as.repeatedTrain(Spikes2[[200]],xlim-c(0,3000))
$OilBl
Error in plot.window(...) : need finite 'xlim' values
In addition: Warning messages:
1: In FUN(X[[4L]], ...) : no non-missing arguments to max; returning -Inf
2: In FUN(X[[4L]], ...) : no non-missing arguments to max; returning -Inf
3: In FUN(X[[4L]], ...) : no non-missing arguments to max; returning -Inf
4: In FUN(X[[4L]], ...) : no non-missing arguments to max; returning -Inf

Fundamentally, this may involve some changes to the STAR package to incorporate a notion of the time window over which spikes were mesasured (even if there were no spikes).