Merge pull request #7502 from skirpichev/move-sets

Move sets.py to sympy.sets (from the core)
Remove deprecated separate function, fix #6482
Remove deprecated Plot function, fix #5944
Remove deprecated argument handling in the checkodesol, fix #6483
clarify inline regarding use of d*m in simultaneous subs

[skip ci]
clarify error statement when diff fails

[skip ci]
Merge pull request #7505 from smichr/const

Const
fix docstring typos in mechanics.functions
pretty printers for BosonOperator and FermionOperator
use _eval_commutator_class instead of testing with isinstance(..., class). Added rule that makes Boson and Fermion operators commute.
Changed print to print() and xrange to range for compatibilty with Python 3
merge with master
simplify Integral.is_number routine
Removed the currently empty section header on Forberg's method for derivatives
Fixed some problems with using print() and pprint.
Fix examples
Further attempts to fix problems with using print, pprint solved.
Merge pull request #7507 from pierre-haessig/mecha-typo

fix docstring typos in mechanics.functions
Cleaned up usage of print, removed pprint. Now hopefully done.
Merge pull request #7504 from skirpichev/remove-deprecated-since-0.7.2

Remove features, deprecated since 0.7.2