[Cython] Dev days status

[Robert Bradshaw]

These last couple of days we have appreciated having Dag Sverre  
Seljebotn and Dan Gindikin (the creator of Pex) around, and have had  
a lot of discussions (if not yet a lot of code). Personally, I have  
been wrapped up in other sage-related projects as well. A good  
summary of the discussion can be found here http://wiki.cython.org/ 
enhancements/pex . We have also decided to change the direction of  
Dag's NumPy GSoC project a bit--to really get what we want it had  
become clear that a better approach will provide direct support for  
buffers http://wiki.cython.org/enhancements/buffer to provide fast  
NumPy array access.

The biggest proposals for change are:

- Having an except [uncommon value]? by default on all implemented  
functions.
- Phasing out cimport, letting import be cimport whenever the  
relevant header files are found.
- Using the .pyx file for "cimport" when a .pxd file is unavailable  
(basically auto-generation of pxd files).

These last two have the disadvantage that the dependancy tree could  
become much more connected, so we would provide a way to disable  
them. Thoughts?

- Robert