Rework infinitesimals docstring.
Fix dsolve reference under Hint Functions.
Fix logcombine reference.
Rework awkward language under constantsimp.
Fix references to several ode functions.
Shorten function references under "See also" headers.
Rewrap with tw=78:et.
Commiting the files for types C, D, E, F, and G
Fixing things
Revert "Shorten function references under "See also" headers."

This reverts commit 203798670ce80881555eee5be9ce625454cc8f60.
Fix reference to separatevars.
Rewrap lines tw=78.
Updating the other types
Rephrase "Hint Functions" and "User Functions" intros.
Merge upstream commits.
AskPositiveHandler.Pow: x**y is positive for x>0 for real y
AskNegativeHandler.Pow: x**y is not negative for x>0 for real y
AskPositiveHandler.Add now works with nonnegative args (one positive is requered)
Drop duplicated assert in test_bounded_xfail()
AskNegativeHandler.Add now works with nonpositive args (one negative is requered)