Make handle and related classes const correct.

Use object class to hold partially converted python objects.

Using object class to hold converted object automatically deallocates
object if an exception is thrown or scope is left before constructing
complete Python object.

Additionally added method object::release() that allows to release
ownership of python object without decreasing its reference count.

Clean the type name alone, not the whole message.

This gives handle classes a typical pointer semantics with respects to
constness.

Add const modifier to handle::cast.

Create an empty python tuple in pybind::tuple default constructor.

Follow the same semantics as constructors of dict, list, and set by
creating valid Python object in default constructor of a tuple class.

functional.h not included in "make install"

Fix typo in STL docs.

ENH: add more error conversions

Fixed py:array constructor from failing for complex types

Add complex.h to list of installed headers

The array(const buffer_info &info) constructor fails when given
complex types since their format string is 'Zd' or 'Zf' which has
a length of two and causes an error here:

if (info.format.size() != 1)
    throw std::runtime_error("Unsupported buffer format!");

Fixed by allowing format sizes of one and two.

Fix typographical errors

Add ldflags to compile command

Add debug appveyor configuration