[Urwid] navigation speed

[Ian Ward]

Rebecca Breu wrote:
> Zitat von Ian Ward <ian at excess.org>:
> 
>> There are also some big improvements that could be made by rewriting the
>> performance-critical sections of code in C.
> 
> That definitely sounds interesting. I have just written a tiny extension in C
> myself. Maybe you could need some help?
> 

Definitely!  I'd love some help here.

Prime targets for rewriting include:
- utable.py functions:
   - get_width
   - decode_one
   - decode_one_right
- utils.py functions:
   - move_prev_char
   - move_next_char
   - is_wide_char
   - calc_width
   - calc_text_pos
   - within_double_byte

Those functions should be fairly easy to convert -- they're already very 
C-like.

Ian