Matrix.det_bareis is sensitive to ImmutableMatrix
sympify args of MatrixExpr functions

Otherwise Matrix objects can creep in
explicitly merge MatrixBases in MatAdds
matmul merge_explicit rule
matadd/matmul: fix doc and unittests

Signed-off-by: Thomas Hisch <thomas.hisch@ims.co.at>
Merge pull request #17 from thisch/mrocklin-matexpr-sympify

matadd/matmull fix unit and doctests
MatMul merge explicit does not commut matrices
Merge pull request #7250 from mrocklin/matexpr-sympify

Matexpr sympify
Drop ancient oseries method
Drop _hashable_content (inherit from Basic)
Order for point's != 0 or oo
Some tests for point != 0 and oo
Alter subs for Order with point != 0 or oo
Fix docstring of Order class
Right series() for x0!=0
Fix expr.series() docstring
Fix O terms for series with x0!=0
Fix example with series for x0!=0 in the tutorial
An example of series for x0!=0
Add examples to doctest