v0.2

• Functions related to tbl and src stay in dplyr (#26). Remove unused make_tbl().
• Non-scalar input to frame_data() and tibble() (including lists) creates list-valued columns (#7).
• Use C++ implementation for as_data_frame.matrix() (#14). Also add former matrixToDataFrame() tests, and fix unwanted conversion to factor.
• as_data_frame(NULL) is 0-row 0-column data frame (#17, @jennybc). frame_data() and tibble() create empty data_frame if no rows are given (#20).
• data_frame(NULL) raises error "must be a 1d atomic vector or list".
• lst(NULL) doesn't raise an error anymore (#17, @jennybc), but always uses deparsed expression as name (even for NULL).
• trunc_mat() and print() use width argument also for zero-row and zero-column data frames (#18).
• glimpse() now (invisibly) returns x, so it can be used within a chain of dplyr verbs (@edwindj).
• base::getElement() now works with tibbles (#9).
• Remove spurious usage of "dplyr" in documentation (#3).
• Almost full test coverage.