Fix bug 7648 comment in `std.stdio.File` and add bug section to `std.file.slurp`.

Issue URL: http://d.puremagic.com/issues/show_bug.cgi?id=7648
Fix Issue 12556 - Add persistent byLine
Make byLineCopy support mutable line copies
Fix caching byLineCopy.front (oops)
std.math: Check if dmd-style inline asm is available
Issue 10194. Variant does not call struct destructors.
Implemented elaborate copying support.
Sanitize Appender constraints a bit.
Clarify when to use byLineCopy vs byLine
Fix issue 3363: std.stream.readf segfaults with immutabel format strings
getoptx

some tinkering

alot more

comments

some more

more doc

getoptX cleanup

tuple -> struct

getoptX -> getoptEx

Required

getoptEx is now inline

GetoptRslt -> GetoptResult

more info

some comment fixes
Merge enforceEx with enforce

Makes it possible to call `enforce!MyException` instead of `enforceEx!MyException`, eliminating
redundant notation. Old enforceEx is not deprecated but removed from documentation examples.
cartesianProduct: default order should be lexicographically sorted.
Update unittest and example code to reflect new ordering.
Get rid of exponential template bloat for most common use case of cartesianProduct.
Mark std.file.writeImpl as @trusted
Mark std.file.rename as @trusted
Mark std.file.remove as @trusted
Fix Issue 13042 - std.net.curl.SMTP doesn't send emails with libcurl-7.34.0 or newer
(last)indexOfNeither(index)

faster

merged indexOfAnyImpl with indexOfNeitherImpl and fixed a bug