Returning large aggregates as values is a potential performance problem, but preventing all aggregate returns is inappropriate because:

1. returning small aggregates that are mostly handled as complete objects as return values often makes code clearer.

2. Modern (well not so modern actually) ABIs allow for small aggregates to be returned in registers, so forcing all returns to memory is actually likely to be slower.

3. if code review does not notice a large aggregate return and nobody notices a performance issue then it doesn't matter

For some reason the TravisCI build has `-Waggregate-return` enabled as
an error even though it's completely valid code. Also constify the
input `color_name` argument to `load_color` function.

* Improve GTK+3 theme loading

- Merge geany-3.0.css into geany.css
- Load geany-3.20.css to override if runtime version dictates
- Load geany.css from app->configdir if it exists.

* Add initial documentation for GTK+ CSS theming

* Add geany.css file to the `Tools->Configuration Files` menu

Also mark such config files as changed if they don't already exist to
force the user to save or discard any newly created config files.

* Allow customizing message window using GTK+ themes

* Improve GTK+3 CSS docs a bit

State which classes are meant to be overridden by themes.

* Go back to conditionally loading geany-3.0.css

It can't be merged into geany.css since GTK+ CSS parser doesn't ignore
invalid properties when prefixed with vendor extension (ie. -Gtk).

* Don't mark unedited config files as changed

They probably should be marked as changed since they don't exist on
disk yet, but for the time being leave it how it was.

* Fix misuse of CSS ID vs class in manual

* Minor colour value tweaks

Based on feedback from @b4n

Show status message on attempt to execute empty context action.

If a user selects "context action" from the context menu then now the status message
'No context action set.' will be shown. Closes #1641.

Add a note for applying the indent settings in the project preferences

Fix the symbols tree hierarchy when several tags have the same name

Add a tooltip showing the full path on menu items representing documents

See:
* https://www.w3.org/TR/css3-grid/#property-index
* https://drafts.csswg.org/css-grid/#property-index
* https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Grid_Layout#CSS_properties

Closes #1705.

Say hello to Geany 1.33 "Gorgon"!

Keep the previous behavior if the user had disabled saving window
position and geometry, by using the existing setting as default for the
new one.

Cancel 'MSG_TYPE_RESAVE' info bar if still open in function 'document_reload_force'.
This closes the "Deleted from Disk" message if the user clicks on the reload button.
Fixes #1330.

Including typo fixes.

* updated it.po

* Small update of metadata on Italian translation

to reflect latest translations updates

* updated lithuanian translation

* Revert "updated lithuanian translation"

This reverts commit e45985679464ed2e495bef6bf16383a472a237c4.

* updated lithuanian translation

* Update zh_CN.po

* Update metadata

This is based upon a suggestion by Andrea on i18n mailing list

Use utils_get_uri_file_prefix() as file URI prefix