Master recall function

[vertesy]

There are quite some variable that are used and stored in the global env.
Upon re-loading a Seurat object, these are missing.

1. I am working on that all are stored in @misc and that all can be individually recalled
2. However a master-recall function could make it easier

Elements to recall

1. p (parameters)
2. gl (gene lists)
3. all.genes
4. meta.tags

[vertesy]

Individual functions are now mostly present:

  recall.parameters()
  recall.all.genes()
  recall.meta.tags.n.datasets()
  recall.genes.ls()

I think I won't take it further. If so, a master backup function would be great too (copy all too @misc).