Changes for next Iris core

Hey,

attached are a collection of changes for the core including:
- a patch to compile position-independent code on ARM architectures
- a patch to change the default logging file and to disable logging to file (useful for embedded targets with flash memory)
- a patch to have the logging levels show up in different colors according to their importance (on console only, file logging has no colors)

Let me know what you think.

Thanks
Andre