DOC: Update after refactor. Use code block.
Merge pull request #2009 from jseabold/cov-struct-docs

DOC: Update after refactor. Use code block.
ENH: Warn on non-convergence.
ENH: Add check_convergence flag to turn off warning
STY: Pep-8
STY: Pep-8. Remove commented code. Remove tabs.
REF: Remove NoseWrapper to avoid circular import
ENH: Always issue our warnings. Closes #724.
TST: Silence ConvergenceWarnings
DOC: Add warnings update to release notes
STY: Change keyword name
TST: Make sure intentional convergence failure happens
TST: Catch warning. Set maxiter low enough not to raise.
REF: Make warn_convergence a kwarg.
STY: Some pep 8
TST: Silence test warnings.
ENH: Do not warn on intermediate results convergence.
TST: Silence convergence warnings in tests.