Update random.d

fix wrong usage in doc example (Random gen(unpredictableSeed)).
Update random.d

fixed spacing
Implement issue# 10314.

This moves std.traits.unsigned to std.conv and adds std.conv.signed,
since for some reason, we have std.traits.unsigned but do not have
std.traits.signed.
Unittesting uriLength and emailLength

Previously untested. Pushes code coverage from 57% to 79%.
Remove debug printfs from std/uri
Style fixes in std/uri

- indentation within blocks
- braces on their own lines
Deglobalize default threshold value, and fix initialization of threshold variable.
Fix Refcounted docs - refCountedEnsureInitialized and refCountedIsInitialized did not exist.
Merge pull request #1379 from AndrejMitrovic/FixupRefcountDocs

[trivial] Fix Refcounted docs
Call thisTid to initialize first thread's message box, bypassing checks against setting thread-local variables from a shared static constructor.
Merge pull request #1369 from AndrejMitrovic/IsemailFix

Deglobalize default threshold value, and fix initialization of threshold variable
Merge pull request #1376 from yebblies/issue4923

initialize first thread's message box in a normal static ctor, to work around requirement that thread-local variables cannot be set from a shared static constructor.
Fix Issue 10517 - readln(Char)(Char[] buf) accepts non-mutable buffers

Also templatizes a global readln
Fix wchar/dchar issue

Just cause a file is nativelly treated as UTF16 (or something), doesn't mean you can iterate wchars.
Fix Issue 10510 - enforce should take any callable function without regard for calling conventions.
Merge pull request #1382 from AndrejMitrovic/Fix10510

Issue 10510 - enforce should take any callable function
Improve iteration scheme for wchar/dchar
Improve restraints for readln
Converted C-style array declarations to D-style
Merge pull request #1381 from monarchdodra/readln

 Fix Issue 10517 - readln(Char)(Char[] buf) accepts non-mutable buffers