Before we used g_get_user_config_dir() but GLib changed the returned
location in newer versions, so use the Windows API directly
to get the old location, at least for now.
Also add utils_get_user_config_dir() wrapper.

Code is based almost completely on a patch from Matthew.

Fix typo in README

Don't use `g_regex_get_compile_flags()` that is new in 2.26, but we
only depend on 2.20.

Closes #340.

Project line wrapping pref

Fix adding stash group and applying defaults.
Don't let Properties dialog override per-document line wrapping state.
Use "editor" for key group name.
Remove code already handled by stash group.

Notify user when trying to save read-only document

Confirm infobar reload when document has modifications

New name is clearer against document_reload_prompt.
Add deprecated alias.

Don't set document text as changed when file on disk is newer

Setting the document text as changed makes it too easy to accidentally
overwrite the file - e.g. when closing you're reminded to save it.
It also makes it slower to close documents you no longer want open.
Setting text as changed is still done if the user cancels the warning.

Confirm whether to save protected documents instead of ignoring save

(Reuses existing strings).

Backport changes applied upstream not to hard-code auto-completion popup
frame border size.

Don't assume changing the style inside a style-set handler results in
recursion, as it would be wrong if the next signal emission was
triggered asynchronously.  Instead, only modify the style if it isn't
already as we want it.

This fixes the about dialog's style-set handlers on GTK 3.10 which
didn't liked constant style updating.

This reverts commit ec707106.

Apparently the selected state of an event box doesn't necessary mean it
will be styled with a selection background color.  This e.g. isn't the
case in GTK 3.14's Adwaita (default) theme.

So, revert the commit that removed custom style overrides.  Next commit
will fix the GTK 3.10 problem this reverted commit fixed.

Useful for when using, for example, GTK+, SDL, and other C-only APIs
in files with the C++ filetype. Before only the symbol auto-completion
worked, but not the highlighting of type names.

TODO: figure out why taking something like SDL.c.tags and making a copy
as SDL.cpp.tags doesn't work, once that's fixed, this extra condition
could probably be removed.

Backport changes applied upstream to fix auto-completion popup sizing.

Backport patches applied upstream to cache auto-completion windows,
hopefully avoiding dead popup windows lying around on GTK3 builds in
some high stress scenarios.