modwt_wvar_cpp: Computes the (MODWT) wavelet variance
In wv: Wavelet Variance

Calculates the (MODWT) wavelet variance

modwt_wvar_cpp(
  signal,
  nlevels,
  robust,
  eff,
  alpha,
  ci_type,
  strWavelet,
  decomp
)

`signal`	A `vec` that contains the data.
`robust`	A `boolean` that triggers the use of the robust estimate.
`eff`	A `double` that indicates the efficiency as it relates to an MLE.
`alpha`	A `double` that indicates the (1-p)alpha* confidence level
`ci_type`	A `string` indicating the confidence interval being calculated. Valid value: "eta3"
`strWavelet`	A `string` indicating the type of wave filter to be applied. Must be "haar"
`decomp`	A `string` indicating whether to use "modwt" or "dwt" decomp