Add note about Issue 7648 to `std.stdio.File`.

Issue URL: http://d.puremagic.com/issues/show_bug.cgi?id=7648
Fix issue in `std.json` when `null` is returned instead of empty string/array.
DDoc -std.stdio: exceptions thrown by C-like API.

Updated documentation for all the C-like member functions \
(and the File ctor) to specify exactly what gets thrown when. 

(note: Exceptions in std.stdio are a mess and should be made 
 more consistent. Also, it seems some member functions that 
 should check if the file is opened do not, but I don't know
 if that might be intentional (as the C functions should fail 
 anyway, resulting in a throw))
Merge pull request #1239 from denis-sh/std.json-improvements-2

Fix issue in `std.json` when `null` is returned instead of empty string/array.
Merge pull request #1252 from kiith-sa/patch-2

DDoc -std.stdio: exceptions thrown by C-like API.
Fix `std.traits.hasElaborateAssign` for static arrays.
Merge pull request #954 from denis-sh/fix-std.traits.hasElaborateAssign

Fix `std.traits.hasElaborateAssign`
Merge pull request #1238 from denis-sh/add-note-about-Issue-7648

Add note about Issue 7648 to `std.stdio.File`.
Remove deprecated std.ctype, std.cpuid, and std.perf.

These were supposed to have been removed before now.
DDoc tweaks and fixes
Merge pull request #1267 from CyberShadow/ddoc-syntax-fixes-4

DDoc tweaks and fixes
DDoc: file.d: Exceptions thrown (except slurp)

Added all missing Throws:, with the exception of slurp,
which might throw pretty much anything
(at least Exception, ErrnoException, ConvException, maybe FormatException, gave up on trying to parse all the called code
(main offenders are formattedRead and the File ctor)).
DDoc (minor): array.d: Appender.shrinkTo throws Exception

Specified that Exception gets thrown (the previous ddoc didn't make sense).
Merge pull request #1269 from kiith-sa/patch-4

DDoc (minor): array.d: Appender.shrinkTo throws Exception
Merge pull request #1268 from kiith-sa/patch-3

DDoc: file.d: Exceptions thrown (except slurp)
add missing dependency
Merge pull request #1270 from dawgfoto/makeDependency

add missing dependency
Merge pull request #1264 from jmdavis/ctype

Remove deprecated std.ctype, std.cpuid, and std.perf.