Improve byChunk, lockingTextWriter doc

Make byChunk, lockingTextWriter return opaque types (but keep those
types public for backward compatibility).
Add byChunk range example.
Also document that ByLine's primitives can throw StdioException.
Make constructors of std.file.FileException @safe or @trusted
Improve speed of to!string for integral types
Fix Issue 5378 - Make File.byLine accept a string terminator

Add an overload of byLine without a default argument for terminator.
Before, byLine!string tried to instantiate "string terminator = '\n'",
which is invalid.

Note: This removes the default arguments from ByLine.this, but the
constructor was never documented anyway (unlike the range primitives).
Add comments for ranges that are no longer documented
cleanup std.regex CTFE hacks, it's working as is now
Fix calling ByLine(file) with default args
Ensure terminator string has Char element type
lockingTextWriter should not be a @property
Use ElementEncodingType!Terminator instead of typeof(terminator[0])
Make std.windows.syserror.sysErrorString @trusted
enable ctRegex tests, fix 3 latent bugs

Bad codegen for Backreferences,
wrong trackers used for nested infinite loops
and even wrong code for '.'
restore "multi-line" behaviour of '.' in ctRegex
catch the wrong test-case
fix faulty multi-line logic of Eol in ctRegex

Also reduce the amount of tests to run to let auto-tester breath freely
Add versioned blocks to partition test-suite in compilable parts
Merge pull request #1464 from blackwhale/ctr-enable-test

Enable ctRegex tests, fix 3 latent bugs
Introduce lookahead for ctRegex
safety of nested lookahead, enable all of R-T tests
Merge pull request #1465 from blackwhale/ctr-lookahead

Lookahead support for static regex aka ctRegex
Merge pull request #1459 from blackwhale/ctr-clean

cleanup std.regex CTFE hacks