+0.8.1 (<date>)
+* degree(), ldegree(), coeff(), lcoeff(), tcoeff() and collect() can now
+ be used with constants and indexed expressions as well, so you can use
+ it to collect by powers of Pi or find the coefficient of gamma~0.
+ Limitations:
+ - it only works with symbols, constants and indexed expressions;
+ trying to find the coefficient of, e.g., "x^2" or "x+y" won't work
+ - it does not know about dummy index summations; the coefficient of
+ gamma~0 in p.mu*gamma~mu should be p.0 but is returned as 0
+ - using the functions on elements of noncommutative products might
+ return wrong or surprising results
+* Added preliminary (re)implementations of color and clifford classes.
+* simplify_indexed(): contraction of symmetric and antisymmetric tensors
+ is zero.
+* Some bugfixes (indexed objects, archive writing).
+