We override 'Marshal::load()' via alias and call it with
a custom auxiliary proc in the alias which sets the encoding
of all demarshalled strings to UTF-8. The case where a user
himself provided a proc to 'load()' is not implemented.
This is definitely a better solution than patching the ruby
source tree. Thanks to github.com/cremno for hints and help!
What can I say. I made a pact with the devil, and paid dearly.
Almost a whole day's worth of debugging, actually. Not again.
If this turns out to be slow we can always optimize the critical
parts (with no variable param count) later, or completely remove it.