OpenSystemsDevelopment / qpdf

* Don't surprise people with deprecation warnings
* Provide detailed instructions and support for the transition

Change "-" to "--" for named parameters.
Remove spaces inside "[ option ]" for optional parameters.
Fix "pdf-mod-info --dump file" to match usage message.

Create the typedefs directly in iterators rather than deriving from
the deprecated std::iterator class.

* Use unique_ptr in place of shared_ptr in some cases
* unique_ptr for arrays does not require a custom deleter
* use std::make_unique (c++14) where possible

None of these are in the public API.

Use get() and use_count() instead. Add #define
NO_POINTERHOLDER_DEPRECATION to remove deprecation markers for these
only.

This commit also removes all deprecated PointerHolder API calls from
qpdf's code except in PointerHolder's test suite, which must continue
to test the deprecated APIs.

PointerHolder will be replaced with shared_ptr, so let people start
moving.

add qpdf_oh_new_binary_unicode_string and qpdf_oh_get_binary_utf8_value