Release 4.6.0 - Wild Parrots of Telegraph Hill

See http://www.imdb.com/title/tt0424565/

"The first half of the documentary film focuses on Mark Bittner's
relationship with the Parrots living on the Telegraph Hill in the center of
San Francisco and how he came to be their caretakers.  He has a name for
each one and gives the audience stories of how he's interacted with them.
Included in these reminiscences, is general background information on bird
life in San Francisco and the various theories on how these South American
parrots came to exist in the Bay Area.

The second half of Parrots deals with the fate of the birds now that Mark
has to vacate his small home for the last three years.  Apparently, his care
of the birds has attracted world wide attention, especially in Europe.
There is never really any tension in the fate of Mark or the parrots since,
as Mark points out, the birds are perfectly capable of taking care of
themselves.  The viewer probably has a little less confidence in Mark
though, as he says he has no idea what he will do." - imdb review by
kasserine (US)
[doc] release_parrot_github_guide.pod: Keep also README.md
Minor edits to correct an error in the documentation. The error caused rurban++'s to incorrectly specify the text to 'Parrot Documentation Releases'. Note: This was *my* error, not rurban++'s.
[doc] Improve the StructView docs a bit
[GH #799] cygwin sometimes hangs at alarm and task

signal delivery is a bit too slow and unreliable on cygwin most of the time
Prefix 'Previous' to 'Parrot Documentation Releases' per rurban++'s suggestion.
Prefix 'Previous' to 'Parrot Documentation Releases' per rurban++'s suggestion.
The init_pmc vtable I added should have been in Packfile PMC, not PackfileView. benabik++ for catching the mistake
replace clang attribute analyzer_noreturn by proper __noreturn__

analyzer_noreturn is only a static analyzer hint, but does not even protect from false
-Wsometimes-uninitialized warnings, with Parrot_ex_throw_from_c*().

__noreturn__ also produces better code.
t/dynpmc/os.t failed on lndir builddir

skip hardlinking a symlink.
build/myconfig maybe a symlink to ../srcdir/myconfig
[GH #804] NetBSD needs Parrot_get_cpu_type added to its misc.c

Add Parrot_get_cpu_type to src/platform/netbsd/misc.c
copied from src/platform/generic/misc.c. Thanks to user he32.
[CAGE] libffi: Initialize nci_arg_ptr if !nci->arity

clang 3.1 svn160959 properly caught:

src/nci/libffi.c:543:9: warning: variable 'nci_arg_ptr' is used uninitialized whenever 'if' condition is false
      [-Wsometimes-uninitialized]
    if (nci->arity) {
        ^~~~~~~~~~
src/nci/libffi.c:645:64: note: uninitialized use occurs here
    ffi_call(&thunk->cif, FFI_FN(nci->orig_func), return_data, nci_arg_ptr);
                                                               ^~~~~~~~~~~
src/nci/libffi.c:543:5: note: remove the 'if' if its condition is always true
    if (nci->arity) {
    ^~~~~~~~~~~~~~~~
src/nci/libffi.c:483:31: note: initialize the variable 'nci_arg_ptr' to silence this warning
    void         **nci_arg_ptr; /* pointers to arguments for libffi */
                              ^
                               = NULL
[codingstd] No cuddled elses.
Move Parrot_cpu_type function out of src/platform/misc.c.

This way, it doesn't need to be repeated elsewhere.  For symmetry,
also remove it out of win32/misc.c and give it its own file there as well.

Patch supplied by Andy Dougherty++.
[CAGE] fix most t/codingstd/copyright.t issues

Only imcc has some Copyright (C) 2002 Melvin Smith <melvin.smith@mindspring.com> left.
Improve an IMCC error message to include just a little bit more information about what register set was received and which were expected. jashwanth++ for running into this error
Document PackfileView.subs_by_tag. benabik++ for pointing out the omission.
Add a packfile api function Parrot_pf_all_tags_list function, to return an RSA of all tags in the packfile. Expose this through the all_tags() method on the PackfileView PMC. Add some missing docs. benabik++ for the suggestion
Move the logic from PackfileView.all_subs() to a new pf api routine Parrot_pf_all_subs, to try and keep all logic in the api and out of the pmc
Add a new pf api function Parrot_pf_all_tagged_pmcs. This returns a hash of tag->pmcs, for all tagged pmcs in the packfile. Expose this through the PackfileView.all_tagged_pmcs.