ENH: DataFrame.from_xy methods are duplicates
Decide what to do with each of these
- [x] deprecate `from_csv` ~~/ change to be exactly like `read_csv`~~ -> https://github.com/pandas-dev/pandas/pull/17812
- [ ] from_dict
- [ ] from_records (see #8161)
- [x] from_items (#18529)

This is just a suggestion: `DataFrame` constructor already supports the things that `from_dict` and `from_records` do (`from_items` is not supported by the constructor, but maybe it should be?). Also `from_csv` does the same thing as `pd.read_csv`.

Since `There should be one-- and preferably only one --obvious way to do it.` maybe these methods should be removed/deprecated?

I know that this would cause backward incompatibility, so maybe just a deprecation warning could be displayed until a future major release that could remove them.
