closes 2775
Cleanup Mul._eval_is_imaginary
Modified printers, added dyadic back
Corrected all tests and ensured running
Tests run okay, mechanics core modified to depend on physics.vector
Interactive printing imports from mechanics
Added module to setup file
Modified arg test for CoordinateSym
Removed private functs from namespace, moved dynamicsymbols
added documentation for discrete RV types
Added vector docs folder
Merge branch 'master' of https://github.com/sympy/sympy into vectormove
Finalised docs:1, rectified doctests
Merge branch 'master' of https://github.com/sympy/sympy into vectormove
Rectified error in documentation
Removed duplicate citations
Implemented suggestions given by Jason
Merge branch 'master' of https://github.com/sympy/sympy into vectormove
Merge branch 'master' of https://github.com/sympy/sympy into vectormove
Changed to absolute import