Fixes #1422.

X-Scintilla-Bug-URL: https://sourceforge.net/p/scintilla/bugs/1920/
X-Scintilla-Commit-ID: 8e0cb37c4972cd66b33293b88031acf453685cfd

api: new function geany_api_version for dynamic languages checking API version at runtime

Avoid gdk_display_get_name() on OS X

Fix search history filling on GTK >= 3.20

Use a per-line cache to avoid re-computing the offset from the start of
the buffer each time. This dramatically speeds up multiple replacements
on large files.

X-Scintilla-Bug-ID: https://sourceforge.net/p/scintilla/bugs/1910/

Update Scintilla to version 3.7.3 plus a fix for a regression on it.

Closes #1320.

On GTK2 and GTK3 < 3.3.6 there is no GtkAccessibleClass::widget_unset()
method, so we can't destroy our accessible object right away.  So, to
avoid accessing a destroyed widget, we need to check whether the widget
still exists in the the ScintillaGTKAccessible destructor.

In other methods it's not necessary because the wrapping GObject class
makes sure not to forward other when the widget has been destroyed, but
we still have to destroy the C++ instance no matter what, so the check
has to be on this side.

Fixes #1410.

This allows plugins to detect the API version of Geany at runtime. This enables
soft dependencies based on Geany's API version, perhaps using a new feature
with a fallback for older API versions. Previously the only alternatives
were hard-depending on a more recent Geany version or ignoring new features.

Really restrict smooth scrolling handling to Wayland.

X-Scintilla-Bug-URL: https://sourceforge.net/p/scintilla/bugs/1901/
X-Scintilla-Commit-ID: ae52e0c68190d423505624ae1d26e442e015d48f

Since GTK 3.19.12, GtkComboBox has an intermediate GtkBox internal
child wrapping the inner GtkEntry.  To get the entry,
`gtk_bin_get_child()` still works as it is part of the API, but the
change breaks the assumption we had that it works the other way around,
that `gtk_widget_get_parent(gtk_bin_get_child(combobox)) == combobox`.
So, while this assumption seemed reasonable, stop relying on it as it
is effectively not correct on GTK 3.20 and newer.

See: https://git.gnome.org/browse/gtk+/commit/?id=222c43fc60362eeb97ce2d5e3a5583a69a2e30ef

More in the comment.

Fixes https://github.com/geany/geany-plugins/issues/462