Scintilla changes:

* Add Message::ChangeInsertion for programmatically setting input method.
  This is helpful on newer versions of macOS, where changing the input method is flaky.
* Handle leading whitespace in XPM images in order to prevent crashes.

diff -r 52d56f79dc0f gtk/ScintillaGTK.cxx
--- a/gtk/ScintillaGTK.cxx	Fri Apr 09 15:11:26 2021 +1000
+++ b/gtk/ScintillaGTK.cxx	Tue Apr 13 16:36:00 2021 -0400
@@ -885,6 +887,11 @@
 		case Message::GetDirectPointer:
 			return reinterpret_cast<sptr_t>(this);
 
+		case Message::ChangeInsertion:
+			// Hijack this interface to programmatically set input method.
+			gtk_im_multicontext_set_context_id(GTK_IM_MULTICONTEXT(im_context), ConstCharPtrFromSPtr(lParam));
+			break;
+
 		case Message::TargetAsUTF8:
 			return TargetAsUTF8(CharPtrFromSPtr(lParam));
 
diff -r 22b6bbb36280 src/XPM.cxx
--- a/src/XPM.cxx	Sat Sep 05 07:55:08 2020 +1000
+++ b/src/XPM.cxx	Fri Oct 02 20:32:13 2020 -0400
@@ -92,6 +92,9 @@
 void XPM::Init(const char *textForm) {
 	// Test done is two parts to avoid possibility of overstepping the memory
 	// if memcmp implemented strangely. Must be 4 bytes at least at destination.
+	while (*textForm == ' ') {
+		textForm++;
+	}
 	if ((0 == memcmp(textForm, "/* X", 4)) && (0 == memcmp(textForm, "/* XPM */", 9))) {
 		// Build the lines form out of the text form
 		std::vector<const char *> linesForm = LinesFormFromTextForm(textForm);