Coding style fixup for PR 2500.

As requested by Andrei.
Wholesale coding style fix for std.numeric.
Make std.file.mkdir safe
Fill in ARM FPSCR stub
Merge pull request #2564 from ibuclaw/armfpscr

Fill in ARM FPSCR stub in std.math
Use std.windows.syserror.wenforce instead of cenforce on Windows
Merge pull request #2552 from quickfur/sumOfLogs_fixup

Coding style fixup for PR 2500.
Don't use built-in .sort in std.base64 unittests
Preemptive fix of other places where .sort is used
Merge pull request #2565 from quickfur/std_base64_sort

Don't use built-in .sort in std.base64 and other places
Fix the documentation for mkdir
workaround inline Issue 7625

- add explicit else branches so that dmd can inline those functions
Fix the arguments for std.windows.syserror.wenforce
Merge pull request #2566 from MartinNowak/workaround7625

workaround inline Issue 7625
Fix 9906: unaryFun and binaryFun should recognize static opCall

Structs or classes with static `opCall` should be recognized as valid
function objects.
Update ddocs.
Revert AA/array extension to unaryFun.

Per PR discussion.
Use inout for ref returning members in std.container.array
Categorize functions in std.math
Remove typedef handling