This commits makes use of source maps and the original source
when printing lacking line coverage in the pretty printer.
Only the executable lines are checked as before (as non-executable
lines will always be ignored anyways). The lines then mapped to the
appropriate source line when a source map is present.
This commit adds basic support for collecting coverage
data using "deno test".
Currently the report is only a text added to the end
of output from "deno test".
