Fix typo
UnXFAIL test_real_Pow

    This test doesn't fail anymore.  And mentioned in docstring
    statements (pi/log(x)).is_real is NOT True (with no assumptions
    on x) long time ago, since commit 6ee8b34.
Fix and UnXFAIL test_rational_products
Fix and UnXFAIL test_wallis_product
Fix and UnXFAIL test_gosper_nan
Karr convention: change limits in doit() for symbolic integers

    This is a small modification for commit dda493
Merge pull request #2315 from skirpichev/misc

Misc small fixes
Automatic series expansion while applying a function
Catch NotImplementedError for f(series), where f is UndefinedFunction
Cleanup
automatic evaluation for multiple arguments
Fixed test failure for log(2+O(x))
Added basic tests for automatic series evaluation
Handle O() with multiple symbols, expand powers with deep=False
Added test: automatic series expansion should't expand anything but terms with O()
Add XFAIL test for log(x + O(x**2))