Fixed compilation with DMD 2.058.

There are some hacks to allow toHash() methods
to be const nothrow @safe, these are due to
Phobos problems (e.g. Variant.toHash() is not const nor nothrow).
Added pure/@safe/nothrow where possible.
Replaced some incorrect 'in' uses with 'const'.
Simplified some Emitter code.
Using std.typecons.Flag where possible, and more in->const.
User defined constructors now can construct all default types (e.g. float).
Fixed a bug that broke mappings longer than 65536 lines.
Updated .gitignore.
Utility function to create a loader from string (avoids API-break in future).
Minor debug message fixes.
Merge branch 'master' of github.com:kiith-sa/D-YAML
	modified:   dyaml/constructor.d
	modified:   dyaml/dumper.d
	modified:   dyaml/emitter.d
	modified:   dyaml/exception.d
	modified:   dyaml/node.d
	modified:   dyaml/parser.d
	modified:   dyaml/representer.d
	modified:   dyaml/scanner.d
	modified:   dyaml/zerostring.d
	modified:   dyaml/constructor.d
	modified:   dyaml/node.d
	modified:   test/src/common.d
	modified:   dyaml/constructor.d
	modified:   test/src/common.d
	modified:   dyaml/exception.d
	modified:   dyaml/representer.d
Fix remaining format errors
Fixed CDC for LDMD2.
Minor formatting fixes.
.gitignore update.
Fixed a minor output formatting bug.