add bin/pharext.update

add bin/pharext.update

Updates the pharext code within an .ext.phar without the real need of re-packaging.

Usage:

  $ ./bin/pharext.update [-hvq] [--] <path ...>

    -h|--help                Display this help
    -v|--verbose             More output
    -q|--quiet               Less output
    --signature              Show pharext signature
    --license                Show pharext license
    --version                Show pharext version
    --   path                Path to .ext.phar to update (REQUIRED) (MULTIPLE)