* 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 ...
* compiler: change s.line_nr in just one place, so that s.last_nl_pos will be updated in tandem too.
* Cleanup spurious spaces.
* Store ScannerPos info inside the cached tokens.
Use the stored information when errors are encountered.
* Fix#2079 ( cannot use type...in assignment ).
* do not store scannerpos per each token, instead rescan the source once on error to get the position.
* compiler: implement highlighting for errors. Use only line/col info stored in the cached tokens.
* fixing building on windows
* Split can_show_color to _nix and _win files.
* compiler: streamline C main function generation
* fix most tests
* compiler: fix for 'go update()' in graph.v . More precise parser error messages.
* Fix temporarily examples/hot_reload/message.v by using os inside it (os.clear).
* Make graph.v easier to quickly modify by defining y outside the loop.
* Fix failure of /v/nv/compiler/tests/defer_test.v when run with 'v -g' (#line directive was not on its own line, but right after } ).
* Do not pass the os.args to tests, even if the tests import os (they are more stable when run in a controlled environment).
* fix declared and not used in the js backend.
* fix js main => main__main too.
* compiler: change s.line_nr in just one place, so that s.last_nl_pos will be updated in tandem too.
* v test v: run repl tests again
* Show gcc version in both windows gcc cases in a) github actions, and b) travis .
* adding inline to is_name_char is_nl and contains_capital does not help actually, just increases slightly binary size.
* Cleanup spurious spaces.
