add dot printing
remove unnecessary pydot import
support styles keyword in dotprint
sorted dict printing - better doctests
sort node/edge strings by length
add test_dot.py
atom, polymorphism, and depth
Changed SPDE from recursive to iterative

changed SPDE function from recursive to iterative as it is called in most of the other functions like(rischDE ,paramrischDE etc)  which on a recursive call makes it difficult to compute ouput because of recursion limit getting exceeded
dotprint traverse handles non_Basics
replaced lines like pow_a = pow_a + 1 with pow_a += 1
Adds test case to test_rde(test_spde)

adds a test case to check *if not c.rem(g).is_zero:  # g does not divide c* raising a NonElementaryIntegralException
Fix init_session(ipython=False) for non-unicode terminals.

InteractiveConsole is another case were we should not force
use_unicode=True. Instead, let's rely on the code that checks
sys.stdout.encoding to automatically set this to the correct
value.
init_printing: Update a comment.
3826: reverse tan double angle
Constant coeff general linear PDE's- first commit
Added references
Rebased and corrected test failure
Implementing TODO 1 and 4- first pass
Hopefully done with all TODO's
issue 3434: warnings from matplotlib when starting isympy
the issue was that matplotlib.pyplot was being imported before
pylab was initialized. initializing pylab after the import of
matplotlib.pyplot caused a warning to be printed to the console.