Changebar port from codeblocks

This patch enables experimental scintilla changebar for geany. For testing only.

Conflicts:
	scintilla/src/CellBuffer.cxx
	scintilla/src/CellBuffer.h
	scintilla/src/Document.h
	scintilla/src/RunStyles.cxx
	scintilla/src/RunStyles.h
Add sidebar tree

This is an implementation of cusomizable sidebar tree. This patch keeps
existing sidebar and adds new option - show documents in sidebar as tree.
Merge remote-tracking branch 'upstream/master' into changebar

Conflicts:
	scintilla/src/Document.cxx
Handle binary files.
callbacks: Refactor on_reload_as_activate() as document_reload_prompt()

The callback wasn't used from glade but is useful for some other places so
it's worth moving into document.c. This also fixes a bug where reload via sidebar
always reloads the current document instead of the actually clicked one.
Avoid passing non-literals to string formatting functions

Having a string literal allows the compiler to check the arguments
match the format, so avoid passing non-literal whenever possible.
VTE: avoid exporting callbacks that are only used internally
Remove prototypes of non-existing callbacks
Don't export callbacks not used from Glade
Normalize callbacks prototypes
Move Glade-only callbacks out of callbacks.h

There is no need to expose the Glade-only callbacks in the header as
nobody uses them directly anyway;  and not having them makes the header
a little less bloated.
Remove redundant toolbar-specific callbacks
Add two missing Glade-only prototypes
Use the appropriate prototype for the window's delete-event callback
Don't manually connect handlers Glade can connect for us

Don't bother manually connecting handlers that Glade can connect for us
just as well.
Move on_clone1_activate() to callbacks.c
Add printf attribute to document_show_message() for better safety

Add G_GNUC_PRINTF attribute to document_show_message() so some
compilers can check the format arguments match the format string.
Fix build warning about missing return value.
Callbacks: get rid of the ugly `insert_callback_from_menu` global
Move include insert callbacks to the UI code where they belong