KroneckerDelta is 0 or 1, thus any positive power returns itself.
Simplify Interval.as_relational().
Handle KroneckerDelta in summations and products.

Fixes issues 3481 and 3482.
Use solve only once on the system of equations.

Use solve only once on the system of equations, instead of calling
it for each equation.
Add initial manual integration implementation
Integration by parts, general improvements
Add documentation
Make parts rule more robust
Python 2.5 compatibility
Add manualintegrate to Integral._eval_integral
Python 2.5 compatibility (again)
Better integration with integrate()
H^2 in separate branch
Issue #3581:Implement arg.rewrite(atan2)
incorporate feedback from pull request
Work around ODE test
fix a typo and lack of spaces in strings split across two lines
revert change
Fix tests
Fix doctest