* support passing --vcrepo and --hyperfine_options. Streamline output.
* Compare the performance of compiling a simple hello world program too.
* Remove redundant vprod comparisons. Instead use v .
* tools/performance_compare is now more robust. It uses the C source from the time of the v commit, instead of always the latest one. It also now clones https://github.com/vlang/vc just once per comparison, not for every build.
* Remove obsoleted tools/compare_v_performance_between_commits shell script.
* compiler: extract and cleanup error handling functionality into its own file compiler/compile_errors.v
* compiler: implement p.error_with_token_index and p.warn_with_token_index and use them. Fix tests.
* tools/performance_compare: add a 'Source lines in compiler/' line
* MSVC does not have STDOUT_FILENO nor STDERR_FILENO ...
