add '.inputObjects' preamble to module template

add the following to the start of `.inputObjects` part of the module code template:

```r
  cacheTags <- c(currentModule(sim), "function:.inputObjects")
  dPath <- asPath(getOption("reproducible.destinationPath", dataPath(sim)), 1)
  message(currentModule(sim), ": using dataPath '", dPath, "'.")
```