* compiler: -g and -debug should always add -g at least in the C compiler by default.
* Set first the C backend debug_options, so that the optimization_options can override them later.
* Implement cleaner named is_debug, is_vlines, is_keep_c and is_cache options (i.e. -g/-cg, -keep_c, -cache v flags).
* Check and reset file/line numbers in the generated main program, only if v.pref.is_vlines is true.
* Add source line numbers to backtraces on linux.
* Fix -g (broken after token caching).
* reset the #line directives after all the v code is compiled
* cleanup p.cgen.line setting inside p.next() .
* Support windows filepaths like "C:\Users\travis\build\vlang\v\v.exe.tmp.c" inside generated #line directives.
* Try to diagnose better windows-gcc failing.
* Revert "Try to diagnose better windows-gcc failing."
* implement and use cescaped_path/1 .
* Use cescaped_path/1 consistently throughout compiler/ .
* 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.
