Pyflakes cleanups to matrices
Add table method to Matrix, and modify the string printer

I took this from Chris Smith's work from pull request #1167. I haven't fixed
any of the resulting test failures yet.
Update lambda printer for Matrix
Update doctests with new Matrix printing

I skipped the agca doctests, because the string printer needs to be updated
(it looks silly now), and the mechanics Sphinx doctests, because I think they
really want to be using pretty printing (to get g' instead of Derivative(g(t),
t)).

I haven't yet touched the regular tests.
Matrix._format_str should be passed a printer, not a function
Update mechanics doctests with updated Matrix printer
Update Matrix printing tests
Update AGCA tests/doctests with new Matrix string printer

This looks a little weird.  We may want to change it.
Add a docstring for Matrix.table
Print single row matrices in one line

**Before**

>>> Matrix([[1, 2, 3]])
Matrix([
[1, 2, 3]])

**After**

>>> Matrix([[1, 2, 3]])
Matrix([[1, 2, 3]])
Use str.ljust, etc. instead of string.ljust

The latter no longer exists in Python 3.
Merge branch 'master' into mprint

Conflicts:
	sympy/matrices/sparse.py
Merge pull request #2088 from asmeurer/mprint

Make str(Matrix) repr-able