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
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.
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
Fixup readln.

Fixes an issue where `readln!S` did not forward the type "S" in `stdin.readln()` => `stdin.readln!S()` (that was my mistake, sorry)

Fixes an issue where `File.readln!S` assumed S was an "immutable string type". This should work:

char[] buf;
buf = myFile.readln!(char[])();

While buf is not reused after each call, there should be nothing preventing the user for mutating if he so (explicitly) wishes.

Added/improved unittests a wee little bit.
Removed empty declarations
Removed empty declarations
Removed implicit string concatenation.
Removed empty declarations.
Merge pull request #1384 from monarchdodra/readln

Fixup readln.
Merge pull request #1341 from jmdavis/signed

Implement issue# 10314 (add std.traits.signed).
Merge pull request #1383 from Hackerpilot/master

Convert C-style array declarations to D-style.
Fixed grammar description of formattedWrite in docstring
Removed implicit string concatenation