added 'error_report()' and 'ci_report()' to printfuncs.py to return text of error / ci reports
fixed tests to use report_errors()/report_ci() imported from lmfit
removed tests/testutils.py
renamed error_report() to fit_report() (and report_fit()), add min_correl, improved formatting
fix typo in fit_report() output, added fit_report()/report_fit() to docs
added report_fit(), fit_report() to lib/__init__.py
updated all tests to use print_report()
updated all tests to use print_report()