Set bin/regreph and bin/bench as binaries in composer.json

[hkdobrev]

• Rename the binaries to remove the .php extensions. It could be confusing if you need to include them in your code or run them on the CLI.
• Make the files executable.
• Add a useful shebang to the top of the binary files.
• Add them to the bin section in composer.json. It is not only informative to the people reading composer.json, but Composer would move them to vendor/bin/ when regreph is installed as a dependency. See https://github.com/sebastianbergmann/phpunit/blob/master/composer.json#L47 See https://getcomposer.org/doc/articles/vendor-binaries.md
• Update examples in the readme.

[staabm]

:+1:

[hkdobrev]

The screenshot is not updated in this PR, but It would be really useful if @lox does that.