Naming rule for user-defined identifers

[nighca]

User-defined identifers include:

• Identifiers defined in user code
• Sprites, which result in struct definitions with the same name in compiled code
• Sprites & sounds, which requires a variable definition with the same name to trigger auto-binding

Rules may be applied in these places:

• Static check by LS
• Name validation when renaming identifiers defined in user code
• Name validation when renaming sprites & sounds
• Creation for sprites & sounds