menubutton: Remove align-widget property

See merge request !2280

The property has been unused since commit 8701e34f. That was four
years ago, so it's safe to say that nobody has been missing it terribly.

gdk/gdkarrayimpl.c: Fix build on Visual Studio

See merge request !2279

It seems like initializing something to an empty array using `{}` is a GCCism,
so just stuff a 0 within the braces to accomplish the same thing.

filechooser: Remove a leftover signal emission

Closes #2942

See merge request !2276

This is truly a russian doll of documentation formats:
a string containing <> inside an xml fragment in an |[ ]|
gtk-doc example in markdown in a doc comment.

Sadly, something gets escaping wrong, so the <> end up
literally in the docbook and mess up the last step of
our document formatting, even after turning them into
entities.

Work around this with an extra level of entities that
really shouldn't be necessary.

This flag causes pandoc to emit a proper doctype
declaration and, crucially, namespace declarations
for the xlink namespace that it insists on using
for href attributes. Without this, putting external
links in md documents doesn't survive the journey
through xml.

Point out the need to escape <> in xml.

Add a reference to the the syntax for shortcut actions
in builder files.

Commit 0145809a replace the response-requested
signal with an action, but didn't actually remove the emission
of that no-longer-existing signal.

Fixes: #2942

Wip/otte/for master

See merge request !2277

Matthiasc/for master

See merge request !2275

Add a table mapping event signals to their event controller
replacements, and a table mapping former GtkContainer
subclasses to their gtk_container_add replacement.

timsort: Actually 0-terminate the array in get_runs()

See merge request !2274

This could cause SEGVs when changing the sort during an ongoing sort
operation.

Massively refactor and improve sortlistmodel

See merge request !2273

SSave the missing keys as a bitset and iterate over that bitset in the
step function.

Solves the problem with a large UI block at the beginning of a sort
operation when all the keys were generated, in particular when key
generation was slow.

Benchmarks for maximum time taken by a single main loop callback:

     initial sort with complex GFileInfo keys
                       old      new
      32,000 items   137ms      3ms
     128,000 items   520ms     31ms

     initial sort with string keys
                       old      new
      32,000 items   187ms      1ms
     128,000 items   804ms      3ms

When updating a (partially) sorted model, take the known runs for the
existing sort and apply them to the new sort. That way, we don't have to
check the whole model again.

Benchmarks:

      appending half the items to a model of strings
                        old      new
      512,000 items   437ms    389ms
    1,024,000 items  1006ms    914ms

      appending 10% of the items to a model of strings
                        old      new
      512,000 items   206ms    132ms
    1,024,000 items   438ms    301ms

      appending 1 item to a model of strings
                        old      new
       64,000 items   1.8ms   0.00ms
      512,000 items     ---   0.01ms

Previously, the sort was not stable when items were added/removed while
sorting or the sort algorithm was changed.

Now the sort looks at the item position (via the key's location in the
keys array) to make sure each comparison stays stable with respect to
this position.

Compares every element as equal.
This is useful when sorters are in an invalid configuration.