Added functions code
Added tests
Added doctests, rectified default params and tests
PEP8 fixes
Rectified errors
Combined get_motion functionality
Removed whitespace
Removed Vector([]) initialization
Merge pull request #2453 from srjoglekar246/functions

Added get_motion_params function to mechanics core
fixed documentation bug as per issue #4029
Add test for issue 3400
Add test for issue 2826
Add _eval_nseries method for expint()
Some tests for expint series
Merge pull request #2495 from perseus0807/4029_iterables

fixed documentation bug as per issue #4029
Add Vinit Ravishankar to AUTHORS/aboutus. Welcome to SymPy!
Merge pull request #2511 from smichr/auth

Add Vinit Ravishankar to AUTHORS/aboutus. Welcome to SymPy!
Merge pull request #2505 from skirpichev/2958-series-for-error_functions.py

Implement missing series methods for exponential integrals (first part of the issue 2958)
Doc changes
Rectified errors in docs