Camera view selector and embed code generation

This update introduces a new camera view selector and embed code generation features.

Changes

• New camera view selector in the viewport.
• New embed code generation from Publish & Share.
• New settings to control shadows parameters on light objects.
• Exporting now consider quality settings (Default, High, Mid, Low).
• Exporting now supports object clones.
• Cloner improvements.
• Object states improvements with materials.
• When saving, if the file was deleted (in another session), a backup is generated.
• Lights and empty objects can now be selected by rectangular selection.
• Lights and empty objects are hidden in play mode now.
• Fixed several hotkey behavior issues.
• Minor fixes and overall improvements.