* Add new kernel cmdline option for setting argv.

- also restructure parsing of old arguments, since they might clash
- we can now pass parameters to the program with qemu by specifying
for example -append "-args '-h'"

* Change kernel cmdline option from -args to --

now everything after "--" will be treated as argv. This reduces the need
for quote-escaping.

* Add short section about qemu's command-line usage to README