Improved some i8/i16 functions for knc

- added 'cast_trunk' and 'cast_zext' sets of functions
- changed the implementation of __masked_store/load_i8/16 so they would also accept nonaligned addresses
- changed fail_db.txt to hide fixed run/compfails

- also, several helper functions (like [] or cout overloads) were created or fixed. This does not affect performance or functionality