PetscHeaderDestroy: call PetscObjectDestroyOptionsHandlers

Otherwise the options handler destroy method never gets called.
PetscPClose: include errno on failure

Fixes use of "%D" for normal int (overflow for 64-bit-indices).
*ViewFromOptions: update documentation, providing disabled man pages

Most uses for these functions are to place diagnostics in the main
execution flow rather than placing it in a normal *SetFromOptions
function that is only executed once.  This commit provides documentation
because the old comments were incorrect, but does not generate man pages
because we'd rather not encourage users to choose this interface.
3.3-tarball: copy over xclude from master & git date command [for docs]
Increase patchlevel to 3.3-p7
Sys: destroy threadcomm after processing -options_table and -options_left

Creation of a PetscObject (like a viewer) implies threadcomm setup, so
we must ensure that the threadcomm is destroyed after the last
PetscObject.
DMPlex: initialize entire hash key instead of hashing uninitialized memory
Mat ex16: permissive option for approximate preallocation
Merge branch 'balay/maint-3.3-p7' into maint
Merge branch 'maint'
examples: remove superfluous header includes
AO: remove outdated unstructured grid example

This example was poorly structured and did not use typedefs correctly.
We now recommend using DMPlex for unstructured grid management, so the
example is no longer necessary.
AO: is a part of petscvec, not petscdm
SF: is part of petscvec, not petscsys
DLL: translate hyphens to dashes in basename for initializer

For example, when adding a library using

  -dll_append /path/to/libfoo-bar.so

we now look for the initializer PetscDLLibraryRegister_foo_bar().
Merge branch 'jed/dll-options'

* jed/dll-options:
  DLL: translate hyphens to dashes in basename for initializer
  PetscPClose: include errno on failure
  PetscHeaderDestroy: call PetscObjectDestroyOptionsHandlers
Merge branch 'barry/fix-xxxviewsetfromoptions'

* barry/fix-xxxviewsetfromoptions:
  *ViewFromOptions: update documentation, providing disabled man pages
  fixed bug where XXXViewFromOptions() used prefix of object rather than appropriate prefix of KSP or SNES
MPIUNI: ignore -hosts and return exit code
Revert "DMPlex: fix initialization of variables in degenerate case"

This reverts commit 607f2c0b861376b28a49c0aa36815452b52ff6fb.

A simpler variant that did not trigger spurious warnings appeared in
c0ed958bc1af89112bbb1f69651.
DMPlex: remove bad "DMMESH" documentation