CLN: simplify series plotting
ERR: Add check for iterators when creating DataFrame

Add test case for iterator data argument

Move the type check up to where other checks are performed

Use asserRaisesRegexp for more specific checking

Add fix to the release notes
Merge pull request #6977 from onesandzeroes/iterator-error

ERR: Add check for iterators when creating DataFrame, fixes #5357
Merge pull request #6876 from sinhrks/cln_plot

CLN: simplify series plotting
TST: test_sum compare of less precise dtypes take 2