Added __le__ comparison to Tuple

Functions added are __le__these functions helps to compare
between two tuples for example
>>> Tuple(1, 3) >= Tuple(-10, 30)
True
>>> Tuple(1, 3) <= Tuple(-10, 30)
False
>>>
Fixed isympy -a and added a test (#3048)
3197: use equals as fallback

    The error message raised when trying to convert an expression to the
    ceiling integer indicates that simplifying the expression might help.
    This message never makes it back to the user and the ceiling of an
    expression just came back unevaluated. Now equals is used as a fall
    back to try simplification to help in the determination.
Merge pull request #1179 from sachin004/comp_tuples

Tuples now have __le__ comparison
[printing] Implement pager_print.

This is a function which invokes an external pager, as determined by the
pydoc module, to print output. It is meant mainly to display long
expressions in a sideways scrolling pager like "less -S".

Try:

>>> e = Add(*[x**n for n in range(100)])
>>> pager_print(e)  # use sideways scrolling
>>> pager_print(e, num_columns=None) # use line wrapping
Merge pull request #1192 from ness01/pretty_pager

[printing] Implement pager_print.
To compute limits of e.is_Pow and resolve issue id #2455

For the limits of the form, limit(1/(x-a)^b, x, a, dir="+/-") and limit(1/(a-x)^b, x, a, dir="+/-") and also limit(1/sin(x^a)^b, x, x0, dir="+/-") , limit(1/cos(x^a)^b, x, x0, dir="+/-") , limit(1/tan(x^a)^b, x, x0, dir="+/-") and limit(1/cot(x^a)^b, x, x0, dir="+/-") shows wrong results when (x0)**a is an integral multiple of pi or pi/2, depending upon where the denominator goes to zero, the answer obtained by finding through current code is wrong.
This patch gives the accurate results.
Necessary test cases are also attached.
Merge pull request #1205 from mattpap/issue3048

Fixed isympy -a and added a test (#3048)
Merge pull request #1208 from tsndiffopera/finallimit

To compute limits of e.is_Pow and resolve issue id #2455
(Retroactively) add Sergiu Ivanov to the AUTHORS/aboutus file.  Welcome to SymPy!
Fix name in AUTHORS/aboutus file
Add Raoul Bourquin to the .mailmap file
Update .mailmap
(Retroactively) add Raphael Michel to the AUTHORS/aboutus files.  Welcome to SymPy!
Update .mailmap

It should now be completely up-to-date.
Add command to top of AUTHORS file to find missing people
tweak equals and is_constant

    equals tries to succeed sooner by replacing a check for number
    (real or complex) with a test for an atom-like expression, e.g.
    pi + pi*x*I. If, after simplification, only bare symbols are left
    then the expression can't go to zero.

    is_constant was taking to long to evaluate some expressions, so
    some modifications were made to how the values are obtained for
    comparison purposes.
tweak unrad: do not use posify

    Posify allows some radicals to simplify to zero when they
    shouldn't. A test for which this happened was added. This
    also raised the issue that expr.as_poly() may fail when
    expr simplifies to a constant during the expansion process
    that poly uses, so this is circumnvented by pre-expanding
    the expression and checking for this condition.
Merge pull request #1224 from smichr/constant

is_constant, equals and unrad modifications
Float(int,'') -> Float

    Since an integer is unambiguous as a form of input, it is
    allowed with the ''-auto digit counting syntax. As described
    in an inline comment, a float that is equivalent to an integer
    (like 1.0 == 1) may have arisen by entering a long decimal
    like .99999999999999 so that ambiguous case is still not allowed.