Added files from previous PR
Added separate method to Vector
Merge branch 'master' of https://github.com/sympy/sympy into newfunctions
Fixed travis errors
fix docstring of is_zero()
update docstring is_zero
Changed lambdastr to dummy symbols if dummify=True

Previously, if the user declared alpha = symbols('\alpha'),
lambdastr would try to use \alpha as a variable. Now all
all symbols are replaced with dummies if dummify is true,
so any string is a valid variable name.

If the user wants to not use Dummy symbols, they can still
set dummify=False, and get direct substitution. This allows
the output to be examined, but will result in a syntax error
in lambdify if a non-valid symbol name is used (such as \alpha)
fix Dummy.sort_key and use it in expr.sort_key

Also, catch any new Numbers that are generated by the rebuilding
of terms in Mul.flatten. Rather than check them at each step of
the way, just handle them once when done traversing the args.
Add support for Equivalent with multiple arguments
Fixed python3 compatibility issues
Give doctest section titles a line of whitespace beneath.
Fix #7206: Equality with matrices.

Equality was changed to support objects with an _eval_Eq method.  This allows
objects to define alternative algorithms for determining equality.  Such a
method was implemented in ImmutableMatrix.
Merge branch 'master' of https://github.com/sympy/sympy into newfunctions
Added raises test to test_scalar_potential
Remove trailing whitespace.
Merge pull request #7281 from Tempel/7206_matrix_eq

Fix #7206: Equality with matrices.
Added taylor_term for sec(x)

Added taylor_term for sec(x).
Added unit tests corresponding to it.

Reference terms can be found here[1][2]

[1]https://www.efunda.com/math/taylor_series/trig.cfm
[2]https://en.wikipedia.org/wiki/Taylor_series

Updated variable usage, fixed formatting

Removed the declarations from the function call.
Added newline at the end.
Space after `,`

Added @cacheit. Fixed comments

Added @cacheit decorater.
Added space after `#` in comment.
Merge pull request #2869 from SDB1323/Equivalent

Added support for Equivalent with multiple arguments in functions
Add early exit in the limit heuristics() for "bad" results with oo

    This does limit calculations in this method more
    fragle, which is good.  An example:
    >>> O(sin(1/x**2).contains(O(cos(1/x**2)))
    True
    was wrong, just because of this limit:
    >>> limit(sin(1/x**2)/cos(1/x**2), x, 0)
    sin(oo)/cos(oo)
Merge pull request #7300 from sushant-hiray/trig_taylor_term

Added taylor_term for sec(x)