* 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.
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