+0.5.3 - ?/7/2008 - bugfix release
+ * many fixes concerning the CProp hiearchy
+ * coercion database simplified
+ * coercion hiding now works properly for coercions to funclass
+ * triangular pullback works better with coercions to the function space
+
0.5.2 - 2/7/2008 - better-usability-for-the-working-constructivist release
* refinement of match fixed to prevent useless unfolding,
head_beta_reduce is used instead of whd ~delta:true