Update to 0.13:

version: 0.13
date: Mon Apr 14 11:08:45 CEST 2014
changes:
- deprecate isl_int
- improved support for multi piecewise quasi-affine expressions
- allow the user to impose a bound on the number of low-level operations
- add isl_id_to_ast_expr and isl_id_to_pw_aff
- add isl_schedule_constraints
- hide internal structure of isl_vec
- remove support for piplib

(wiz)