added reporters ListReporter and MultiReported and their tests, new test for test_dir, fixed 2 bugs in source_dir(), factored out code from test_dir and test_file into .test_file, made all test function to invisibly return a summary df, changed parent environment of test evaluation environment to parent of globalenv()
implemented some hadley's reviews, added items to NEWS
new code review fixes: comment for parent.env(globalenv()), prettified dput data frame output
removed item test_dir tested from NEWS
added test for source_dir(), fixed a bug I introduced, and made sys.source2 to invisibly return the eval result, so that source_dir() returns it too, useful for testing
used proc.time() instead of Sys.time(), and output the three elapsed times: user, system and real
oups, forgot the test file for source_dir test
adapted tests and generated doc
merged from testthat hadley master
Merge pull request #106 from kforner/master

Return test summary report as a data frame