IEEE-754R 5.7.2 General Operations is* operations (except for isCanonical).

Specifically the following work was done:

1. If the operation was not implemented, I implemented it.

2. If the operation was already implemented, I just moved its location
in the APFloat header into the IEEE-754R 5.7.2 section. If the name was
incorrect, I put in a comment giving the true IEEE-754R name.

Also unittests have been added for all of the functions which did not
already have a unittest.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183179 91177308-0d34-0410-b5e6-96231b3b80d8