initial commit.
doap: add programming language.
doap: add description field.
build: add missing ax_check_compile_flags.m4

This is being used for checking compiler flags when
--enable-maintainer-flags.
editor: default snippet filename for unsaved files to empty string.
snippets: add chdr.snippets for header snippets.

Now we can use `gobject` for both the header and the source file.
editor: default settings to 2 space tabs and indent.
snippets: plumb if snippets should insert tabs.
snippets: ensure GbSourceSnippet knows about tab_width.
snippets: rename tab_size to tab_width to match gtksourceview.
snippets: respect insert-spaces-instead-of-tabs upon snippet insertion.
Revert "snippets: ensure GbSourceSnippet knows about tab_width."

This reverts commit 2725118cde1fa85cde936ed4653ab52ea71cef1e.

Conflicts:
	src/editor/gb-source-view.c
Revert "snippets: plumb if snippets should insert tabs."

This reverts commit a3925a193df0b2b67c1bf27bcb7809a0809b1eb8.

Conflicts:
	src/editor/gb-source-view.c
snippets: fix snippet insertion when tabbed in.

This ensures that the line prefix will match the line where the snippet
was inserted for each subsequent line.
snippets: but don't break non-prefixed lines.
source-view: add push-snippet and pop-snippet signals.

This will allow us to hook into the snippet context from the editor tab,
which is where things like filename should be owned.
source-view: remove filename variable knowledge from source-view.
document: remove unneeded properties and funcs from document.

This stuff will live outside of the document, in the editor tab using
newer GtkSourceView components like GtkSourceFile.
editor: stub out location for snippet variable loading.
editor: remove unused editor title

This will come back when we add the GtkSourceFile "file" property to
GbEditorTab.