Improve color scheme by making it more accurate to Godot color scheme.

Missing entries that I've found so far :

• Pre-existing classes
• Pre-existing types
• Classes properties
• Global functions
• StringNames
• Autoloads colored as classes

Entries I personally think could be added :

• Operators
• Constants
• Enums (but could use same as Classes)
• Brackets/Parenthesis/Braces
• Private/Public members distinction
• Static methods