Cross references between the various f(z)-integral functions
Add 'Li(z)' to the docs
Fix typo
Merge branch 'master' into new-polys

Conflicts:
	sympy/integrals/tests/test_risch.py
	sympy/printing/pretty/tests/test_pretty.py
polys: Added support for <, <=, >, >= to FracElement
Note that substitution does not change the variable either
Add a basic index for the new tutorial
Add new tutorial to the main index
Fix typo
Merge branch 'master' into tutorial

Conflicts:
	doc/src/tutorial/tutorial.en.rst
Start the solvers section of the tutorial
polys: sring([f_1, ..., f_n]) gives (ring, [p_1, ..., p_n])
Update graphviz diagrams with output from my dot-printing branch
Update the invariant for empty args
Fix a typo
Some cleanup to what I have so far in the advanced expression manipulation section
Reorder() Implemented. Tests updated.
polys: Set default order in PolyRing and FracField
polys: Fixed multiplication in K[X](Y) (FracElement)
polys: construct_domain([x, sqrt(x)]) gives EX