port to Windows & MSVC

[mattkretz]

Simple request: Vc and all its unit tests and examples should build and pass with the latest MSVC compiler.
Complex task: MSVC has a lot of quirks in it's implementation/interpretation of the C++ standard. Therefore, lot's of C++(11) code in Vc that builds fine on all other systems fails with incomprehensible error messages when MSVC compiles it.

This issue will be used to collect

1. the shortcomings of MSVC
2. possible workaround
3. necessary trade-offs
4. bug reports submitted to Microsoft

Issue table

Issue	Workaround	Bug Report
In some cases MSVC will see a hard substitution failure when Vc::enable_if<X> is used instead of doing SFINAE.	Substituting Vc::enable_if<X> with typename std::enable_if<X>::type makes SFINAE work again.
Explicit template instantiation of operators of template types normally requires the template keyword before the operator. MSVC rejects the template keyword.	Remove the template keyword. This incorrect code does what is intended.	2591761
Use of class member types in member function arguments outside of the class declaration fail the build.	Replace the short type with the long type expression it aliases.
Use of unqualified type names is sometimes considered ambiguous if the type name exists in at least two namespaces.	Fully qualify the namespace.
Use of constexpr functions in template arguments is considered not a constant expression.	Use a constexpr variable.	2390989
A mismatch of the template parameter names in the forward declaration and declaration of a class template can lead to compilation errors.	Use the same names for the template parameters.
Subtle differences in overload resolution rules. I cannot say I have understood the MSVC rules.	#ifdef some overloads by guessing until it compiles
Long function names are truncated. Long function names can be generated from huge Typelist template arguments.	Pray and hope that no name clashes will occur.
Function parameter types may not use alignas, or other means of over-alignment.	Use the __vectorcall calling convention
A deleted function used in template deduction can lead to a hard failure instead of SFINAE.		2229371 (Fixed in 2015 Update 2)
Compilation errors point to unrelated code.	Curse and do random edits until it compiles.
MMX intrinsics don't compile even though <mmintrin.h> is included.	Rewrite the code without MMX.
sizeof(expression_that_fails_substitution<T>) is evaluated to be 0 and the enclosing expression evaluated. If the this happens to be the denominator of std::ratio, then a static_assert is triggered. Instead the function should have been removed from the overload set via SFINAE.	Add a wrapper around the construction of std::ratio to ensure its denominator argument is never 0.
Using a typedef alias for a class template function definition outside of the class declaration does not compile	Replace the short alias name with the fully qualified class template with according template arguments.
The empty parameter pack case in recursive implementations of variadic template functions complains about a missing function definition.	Add incorrect overloads for the case of empty packs.
Member function implementations inside the class template declaration cannot call member functions of the same class template but with different template arguments.	In some cases it helps to move the function definition after the class declaration. In other cases I found no workaround and had to rewrite the code with an inefficient store - load algorithm instead.

[mattkretz]

For the most part, this issue is resolved. There are a few remaining failing tests and 32-bit Windows doesn't compile at all. Those issues should get their own github issue, though.