Update default theme definitions with multiple file support

* Component: Theme
* Define font as separate asset
Remove @import call from default theme

* Font loaded separately
THM: Add methods for adding multiple assets
THM: Cleanup default theme definitions

* Fix: Font added to child theme instead of default theme
THM: Remove `set_client_style()` (Deprecated)

* `set_styles()` used instead
Refactor `Theme::add_assets()` into `Base_Object::add_files()`
Util: Allow arrays to be passed to `add_prefix()` and `get_prefix()`
THM: Load files in client
Optimize order of client output

* Output client script before other plugin-specific footer output
THM: Update client script output
THM: Refactor default theme client script for updated implementation

* Pass theme properties to `View.extend_theme()`
THM: Refactor `View` library for compatibility with updated theme loading methodology

* Client script/style no longer loaded via AJAX
* Add: `extend_theme()` method
Merge branch 'thm-opt-assets' into develop
Fix: Optimize `has_attribute()`
Add baseline theme
Remove transitions from baseline theme
Update baseline layout
Update baseline styles
Update default theme styles
Update default theme transitions

* Optimized sequencing
* Faster resizing