meltMyTS: Use 'reshape2"s 'melt' on multivariate time series object
In jgabry/QMSS_package: Quantitative Methods in the Social Sciences

meltMyTS is primarily designed to prepare data to be used with ggMyTS (QMSS) to make plots of time series trends with ggplot.

1	meltMyTS(mv.ts.object, time.var, keep.vars)

`mv.ts.object`	A multivariate time series object created with `ts`.
`time.var`	A character string naming the time variable.
`keep.vars`	An optional character vector with names of variables to keep. If `keep.vars` is not specified then all variables in `mv.ts.object` will be kept. However, if any variables are named then all other variables will be dropped, except `time.var`, which is always kept.