Public API typing cleanups
Fix API testcases to match public API typing fixes
Runtests public API typing fix trivia
More public API typing cleanup

Note: use duk_ret_t for function/method/safe call returns, and use
duk_bool_t for "C boolean" returns, where the return value range would
be the same as e.g. a comparison (a > b).
Public API typing changes: get/require/to, codecs
API test case fixes related to API typing cleanup

duk_get_type() return value type related.
Public API typing cleanups, mostly property access
Release note update
Midcommit on typing dev notes
A round of public API typing fixes

All public calls have now been fixed to some extent (FIXME notes left
behind for issues to resolve).
Internal API typing rework
Add type wrapped duk_ptrdiff_t
Code issues update: duk_bool_t, funcptrs
Minor typing changes

Change array type back to unsigned (accidentally changed to signed
previously).  Make codepoint types "fast integer" variants, as they're
used in loops and such, and are not used in significant structs.  This
increases code footprint by ~200 bytes but is the better choice as it
also simplifies API typing.
Typing work and other cleanups on API func docs
Typing updates on API defines doc
Unfinished duk_xmove() API doc
Make duk_errcode_t guaranteed 32 bits wide

This is needed because user error code space is promised to be
[1,16777215] and there also needs to be room for flags which
share the same argument.
Clarify duk_substring() offset argument names
Update internal code issue w.r.t typing