Fixing VC build, apparently MSVC implementation of std::is_default_constructible had no bool() operator

Adding documentation for value_error. Fixing various formatting issues. Removing redundant binding for C++ style methods. Adding bindings for iterator and slicing protocol. Extending examples.

Adding Python-style modifiers for vector. Wrapping has_insertion_operator_implementation in _MSC_VER ifdef’s. Adding ‘!=0’ instead of bool cast’s.

add extra constructors in numpy.h

Compilation issue fixed

This somewhat heavyweight solution will avoid size_t/long long/long/int
mismatches on various platforms once and for all. The previous template
overloads could e.g. not handle size_t on Darwin.

One gotcha: the 'format_descriptor<T>::value()' syntax changed to just
'format_descriptor<T>::value'