[mathiasrw]

Closes #742

Change

• The engine never touches the process. It resolves with a status report, or throws a panic when the run can not go on. Only src/cli.ts sets the exit code and ends the process.
• The status report: files.searched, files.updated, pipe (bytes, type, updated), warnings and errors. It is collected as the run goes, also when the quiet flags hide the messages.
• die() and --halt throw a panic in place of process.exit(). The engine adds the status so far, and the CLI exits with 1.
• --status prints the status report as JSON with an indent of two spaces, after a line break. --status-compact (-S) prints it on one line.
• With --verbose the status report also has engine: the version, the runtime, the config as it came in, what the regex engine was asked to do and the steps of the run.
• --debug (-d) prints only the status report, with what went into the engine and what it did.
• --quiet does not hide --verbose. --quiet-total hides it.
• The debug output along the way (debug(), step()) is removed. The three lines that only --debug showed are now told by --verbose.
• The CLI runs without an IIFE, and reads stdin with on('data').

Tests

• rr() in test/js/helper.js still gives {out, err, exit}. rrStatus() gives the status report of the same run. A spy on process.exit fails the test if the engine ends the process.
• test/js/fix/742.test.js tests the status report, the pipe types, panics, the engine part and the CLI flags.
• test/js/debug.test.js tests the new --debug with the CLI.