Improve some diagnostics

[robotboy655]

Fixes #36

List of changes:

• CSEnt inherits Entity
• WEAPON inherits Weapon
• Weapon inherits Entity
• NETVERSIONSTR global
• SENSORBONE, TEXFILTER enum globals
• string empty default values are imported correctly

Some considerations:

• Perhaps enum globals should be automatic somehow?
• local Weapon = {} is duplicated in the output. Not sure how to handle this, given that, at least on Windows, you cannot have the same file with different capitalization (class.WEAPON.lua and class.Weapon.lua)

[luttje]

Thanks for this additional PR. Much appreciated!

I'll create an issue based on your considerations.