Implement dump_text() and load_text() methods to interact with data.frames?

[gregorgorjanc]

This would open up better understanding and engagement with users,
but it's likely crossing the R vs reticulate Python boundary
we set out at the start.

See https://tskit.dev/tskit/docs/latest/python-api.html#tskit.TreeSequence.dump_text (and https://tskit.dev/tskit/docs/latest/_modules/tskit/trees.html#TreeSequence.dump_text) and https://tskit.dev/tskit/docs/latest/python-api.html#tskit.load_text (and https://tskit.dev/tskit/docs/latest/_modules/tskit/trees.html#load_text)

Perhaps having ts$dump_text() could produce easy to use data.frames?

Explore and rethink this.

[gregorgorjanc]

This would be less efficient version of #49

[gregorgorjanc]

See also what gaia does regarding ts->data.frame #141 (comment)